PhD Research Project: DiMeN Doctoral Training Partnership: Find-me and eat me: understanding how si

Billions of cells die by apoptosis within our bodies on a daily basis. This process of programmed cell death is fundamental in sculpting our bodies as we develop, and in maintaining homeostasis. We now know that clearance of apoptotic cells (efferocytosis) not only disposes of effete cells, but also trains our immune system, helps terminate inflammatory responses and reprograms innate immune cell function. These important roles are conserved through evolution down to flies (Weavers, Evans et al., Cell 2016). Failures in efferocytosis are associated with chronic inflammatory conditions (e.g. chronic obstructive pulmonary disease, COPD) and damaging autoimmune conditions in humans and impaired immune responses in flies (Roddie and Evans, in preparation).

Vertebrate macrophages are thought to detect and migrate towards apoptotic cells via the release of diffusible “find-me” signals (e.g. ATP, UTP; Ravichandran, Immunity 2011). This migratory response leads to phagocytosis and subsequent degradation of the macrophages’ apoptotic cell prey. Nonetheless find-me cues remain poorly studied, particularly in vivo. We believe such cues exist in Drosophila and will use this highly genetically-tractable organism, in which apoptosis and macrophage migration can be imaged simultaneously, to dissect genetically how macrophages detect dying cells. Drosophila is a proven system with which to tackle the problem of innate immune regulation, with the Nobel Prize for Medicine awarded in 2011 for its contribution to the discovery immune activation via the Toll family of receptors.

Understanding how innate immune cells such as macrophages detect apoptotic cells will provide an insight into both basic innate immune cell function, but is also relevant to a broad range of human diseases in which chronic inflammation co-exists with large amounts of cell death (e.g. cancer, chronic wounds, atherosclerosis, COPD). It is therefore likely that find-me signals released by apoptotic cells will contribute to the recruitment, maintenance and inappropriate behavior of disease-associated macrophages at these sites of pathology.
This project takes an interdisciplinary and translational approach to study how macrophages detect dying cells in vivo and how this process may be exploited for therapeutic potential. The project can be broken down as follows:

1a. We will take an in vivo, live imaging approach to visualise interactions of apoptotic cells and macrophages in the developing Drosophila embryo. These movies will then be used to inform a modelling approach to understand the nature of find-me cues in vivo.

1b. In parallel, we will use Drosophila in a genetic screen to uncover novel regulators of how macrophages find apoptotic cells.

2. Evolutionary conservation of novel cues will be probed using human macrophage migration and efferocytosis assays. It will be particularly fascinating to discern how find-me cues are integrated with other signals already known to regulate macrophage migration.

3. Finally, we aim to translate our findings to a model of human disease and will investigate the effects of find-me signals in the context of chronic inflammation by challenging macrophages derived from COPD patients in migration and efferocytosis assays.

In summary, given the broad range of processes and diseases upon which regulation of efferocytosis impacts, a greater understanding of find-me cues and how they influence cell behaviour will bear significant relevance to both medicine and discovery biology.

This project involves training in Drosophila genetics, state-of-the-art live imaging, macrophage cell culture, migration assays and mathematical modeling. In depth training will be provided for all elements and there is scope to focus more either on modelling or biological experiments in the final year. Previous experience of mathematical approaches to study biological problems would be considered useful but is by no means an essential criterion since close supervision will be provided for those experiments. This work will be primarily based at the University of Sheffield. For further information please contact Dr. Iwan Evans (i.r.evans@sheffield.ac.uk).

Second supervisor: Dr. Lynne Prince (Sheffield)
Third supervisor: Dr. Roman Bauer (Newcastle)

Web links:
http://iwanrevans.weebly.com
http://www.sheffield.ac.uk/iicd/profiles/iwanevans

Funding Notes

DiMeN DTP studentships are funded for 3.5 years and include:

- Tax-free maintenance grant set at the UK Research Council's national rate.
- Full payment of tuition fees at the Home/EU rate.
- A Research Training Support Grant to support your research studies.

Successful Home students will receive a full studentship. EU students will be considered for a full studentship/fees only support depending on the excellence of their qualifications and their employment/residency status.

Please carefully read the instructions on eligibility and how to apply at our website and use the link on the page to submit an application: http://www.dimen.org.uk/how-to-apply/application-overview

References

Evans IR & Wood W (2014) Drosophila blood cell chemotaxis. Current Opinion in Cell Biology 30:1-8.
Ravichandran KS (2011) Beginnings of a good apoptotic meal: the find-me and eat-me signaling pathways. Immunity 35:445-55.
McCubbrey BS & Curtis JL (2013) Efferocytosis and lung disease. Chest 143:1750–1757.
Weavers H et al., (2016) Corpse Engulfment Generates a Molecular Memory that Primes the Macrophage Inflammatory Response. Cell 165:1658-71.