MRC Precision Medicine DTP: Characterising neutrophil reverse migration using experiments and models

Background
Neutrophils, abundant circulating leukocytes that form a first line of defense against infections, are an important component of the innate immune system. When activated, neutrophils leave the bloodstream to migrate to sites of infection or injury, following gradients of chemoattractants or chemokines in a process called chemotaxis. Neutrophil reverse migration, or retrograde chemotaxis, is their migration away from a chemoattractant rather than towards it. This has been described in vitro and in vivo. Reverse migration might promote the resolution of inflammation, but it has also been shown to promote inflammation at distal sites [Nourshargh et al 2016]. Whilst neutrophil chemotaxis has been the subject of intense research for decades, the regulation of reverse migration remains elusive. Mechanisms suggested to mediate reverse migration include receptor desensitization, chemattractant breakdown and changes undergone by post-migrated neutrophil.

In an extension of an existing collaboration between the Insall and Vermeren labs, this project will use a combination of wet [Chu et al 2016; Chu et al 2018] and dry science [e.g. Tweedy et al 2016] to test how neutrophils negotiate reverse migration. Building upon a current mathematical model, this project will test whether the regulation of reverse migration depends on metabolic break-down of chemoattractants to generate chemorepellents.

The proposed will work towards identifying how neutrophil reverse migration could be therapeutically targeted.

Aims
The student will explore the molecular mechanisms underpinning neutrophil reverse migration by using a combination of bespoke chemotaxis assays performed with freshly prepared neutrophils (Vermeren lab) as well as computational modelling (Insall lab). By doing this, they will:
- compare the chemotactic behaviour of basal and activated (post-migrated) neutrophils with regards to chemotaxis and reverse migration;
- identify differential expression of chemokine receptor expression and chemokine generation by such cells.
- Construct detailed new models in which neutrophils respond to chemokines, using parameters measured from real cells. As a starting-point, parameters from IL-8 chemotaxis will be used.
- Use the results of the models to design and build improved chemotaxis chambers (e.g. labyrinths with dimensions specified by the model results and concentrations of attractants that work best) to observe reverse migration of primary human neutrophils by light microscopy;
- if the models involve chemokine metabolism, identify the enzymes responsible, knock them out in cultured neutrophil-like cells and characterise their chemotactic phenotype.

Training outcomes
The project will suit a student with a science (biology/physics/maths) degree and a broad interest in both experiments and theory. The student will be fully trained in cell biological and immunological analysis of signalling as well as computational modelling; they will become effective users of both. The supervisors are experienced in this type of cross-disciplinary training.

The student will prepare basal (and post-migrated) neutrophils and set up chemotaxis assays; they will learn a range of computational modelling techniques that are applicable to biology (first year). From their second year, they will examine chemotaxis of basal and post-migrated neutrophils microscopically, quantitate their results and use existing mathematical models, and if appropriate generate their own new ones. This will identify more informative experimental set-ups (e.g. chemotaxis chambers, experimental conditions to be tested), the findings from which will in turn be used to generate improved models.

The student will thus receive truly cross-disciplinary training and be in an ideal position for a career developing mathematical understanding of complex processes.
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This MRC programme is joint between the Universities of Edinburgh and Glasgow. You will be registered at the host institution of the primary supervisor detailed in your project selection.

All applications should be made via the University of Edinburgh, irrespective of project location:

http://www.ed.ac.uk/studying/postgraduate/degrees/index.php?r=site/view&id=919

Please note, you must apply to one of the projects and you should contact the primary supervisor prior to making your application. Additional information on the application process if available from the link above.

For more information about Precision Medicine visit:

http://www.ed.ac.uk/usher/precision-medicine