TBC

Neutrophils represent a major arm of the innate immune system that can tailor their behaviour to support organ homeostasis and mount tissue specific and transcriptionally regulated inflammatory response [Ballesteros et al, Cell 2020]. Recent developments in the field emphasised that during inflammation neutrophils in circulation and tissue are presented as functionally, morphologically, and behaviourally heterogeneous cells [Wang et al, Nature Reviews Rheumatology 2022].

Increased neutrophil production driven by infection, injury, inflammation or cancer (emergency granulopoiesis) leads to the mobilisation of both mature neutrophils and immature neutrophil precursors into the blood and affected sites, increasing phenotypic and functional diversity. We identified multiple neutrophil subsets in the human blood, based on nuclear morphology and cell surface receptor expression, in patients with giant cell arteritis (GCA) [Wang et al, JCI Insight 2020], severe COVID-19 [Covid-19 Multi-omics Blood Atlas (COMBAT) Consortium, Cell 2022] and sepsis [Kwok et al, Nature Immunology 2023].

One state depicted cells with an unusual nuclear morphology, characteristic of immature neutrophils, extended life span, high level of reactive oxygen species (ROS) production and ability to damage vascular wall [Wang et al, JCI Insight 2020].

This project will dissect whether these identified human and mouse neutrophil subsets exhibit distinct behaviour in the vasculature and tissue microenvironment and whether there are common inter-species signatures. We will develop a 3D microvessel system, using primary neutrophil subsets from healthy participants, in which an endothelial vessel is perfused with neutrophils in a membrane-free and tubular manner against a collagen hydrogel with a chemotactic trigger (chemokines or other tissue cells).

Using this system and confocal microscopy, we will (1) monitor the interactions of neutrophils at different maturation stages with the vessels; (2) examine the effect of neutrophil ROS and NET generation on vascular damage; (3) examine recruitment and migration of neutrophils through an extracellular matrix; (4) assess existing and new drugs under development which inhibit identified molecular regulators for their effect on neutrophil function. To validate the in vitro design and data with live tissue settings, we will use 3D imaging on tissue ex-plants assisted by the Light Sheet Microscopy (LSM), and undertake in vivo validation using human immune challenge paradigms.

Neutrophil activity in the vasculature contributes to increased inflammation in ageing and is relevant to our responses to microbial insults and auto-immune diseases. By characterising human neutrophil subsets causing vascular damage, we will unravel novel biomarkers that will hopefully permit early disease diagnosis, monitoring, and the use of personalised therapeutic regimens.

This project is expected to present a novel organ-on-a-chip model for assessing the effect of new drugs and/or molecular perturbations in both mouse and human settings. This model will be a valuable tool for understanding immune cell migration across tissue, and will also be applicable for research of other immune cells.

This project provides a unique opportunity to bridge discovery and translation, integrating academic and biotech perspectives on the project development, milestones and outcomes, as well as an opportunity to contribute to real-world decision making by testing newly developed reagents in the tissue-on-a-chip system.