Understanding how neutrophils self-organise their migration to sites of inflammation in vivo
type: CreativeWork
description: Neutrophils are major effectors of acute inflammation and microbial defence. Their infiltration and migration in injured tissue are critical for the inflammatory response. They are often observed navigating in a highly co-ordinated and directed manner leading to their aggregation at the target site of infection. This self-organised cell gathering is referred to as swarming. It is known that neutrophil swarming is driven by autocrine attractant production, notably of the lipid leukotriene B4 (LTB4). The decision to release attractants at the single-cell level is important and impacts the magnitude of the entire immune response. However, the precise mechanisms triggering this decision remain unclear. In this study, I employed in vivo imaging of zebrafish larvae to reveal the molecular processes that trigger the release of LTB4 and initiation of swarms. I developed a 2-Photon laser wound assay to elicit and visualise neutrophil swarming. A major limitation in previous studies of neutrophil swarms was the lack of tools to understand cell signalling dynamics during the response. To overcome this, I generated a new biosensor to probe for calcium levels in neutrophils as it correlates with the production of chemoattractants. Using this new tool, I revealed that neutrophils clustering at the target inflammatory site are experiencing sustained high calcium elevation. Using a new probe to follow the production dynamics of LTB4, I demonstrated that the rise of intracellular calcium promotes the biosynthesis of this key attractant. I further demonstrated that these calcium fluxes are triggered upon contact with necrotic tissue. This prompted me to interrogate the damage molecules driving these calcium signals in neutrophils. I discovered that the calcium fluxes were mediated by ATP that binds gated ion channels (P2X1) leading to rapid intracellular calcium uptake. Surprisingly, I found that live neutrophils can also trigger this calcium flux in other neutrophils upon mutual con…
abstract: Neutrophils are major effectors of acute inflammation and microbial defence. Their infiltration and migration in injured tissue are critical for the inflammatory response. They are often observed navigating in a highly co-ordinated and directed manner leading to their aggregation at the target site of infection. This self-organised cell gathering is referred to as swarming. It is known that neutrophil swarming is driven by autocrine attractant production, notably of the lipid leukotriene B4 (LTB4). The decision to release attractants at the single-cell level is important and impacts the magnitude of the entire immune response. However, the precise mechanisms triggering this decision remain unclear. In this study, I employed in vivo imaging of zebrafish larvae to reveal the molecular processes that trigger the release of LTB4 and initiation of swarms. I developed a 2-Photon laser wound assay to elicit and visualise neutrophil swarming. A major limitation in previous studies of neutrophil swarms was the lack of tools to understand cell signalling dynamics during the response. To overcome this, I generated a new biosensor to probe for calcium levels in neutrophils as it correlates with the production of chemoattractants. Using this new tool, I revealed that neutrophils clustering at the target inflammatory site are experiencing sustained high calcium elevation. Using a new probe to follow the production dynamics of LTB4, I demonstrated that the rise of intracellular calcium promotes the biosynthesis of this key attractant. I further demonstrated that these calcium fluxes are triggered upon contact with necrotic tissue. This prompted me to interrogate the damage molecules driving these calcium signals in neutrophils. I discovered that the calcium fluxes were mediated by ATP that binds gated ion channels (P2X1) leading to rapid intracellular calcium uptake. Surprisingly, I found that live neutrophils can also trigger this calcium flux in other neutrophils upon mutual con…
author: Poplimont, Hugo Clément Geoffrey
language: en
keywords: Neutrophil, Swarming, Inflammation, Infection, Optogenetic, Zebrafish, Microscopy, Live imaging, LTB4, Connexin, Calcium
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/533c5aa8-fbbb-4a71-9040-cc129e257c27/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2020-05-16
date modified: 2026-07-22T22:24:17Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.49276