Pathways underlying resistance to infection: Dysregulation of gut homeostasis by damage associate signals.

The cells lining our gut, the epithelium, are a crucial barrier that protects the host from the external environment. The epithelium must be adapted to not respond to the commensal bacteria and dietary antigens it is exposed to. However the gut is a major site of pathogen entry so the gut must be able to switch from tolerance to inflammation when needed. Further, microbial colonization carries with it the risk of infection and inflammation if epithelial or immune cell homeostasis is disrupted. Dietary change, infection or antibiotics can promote release of damage associated signals (DAMPs), such as ATP, that initiate an inflammatory response. This is a similar scenario to that found in the aging population characterised by increased levels of circulating DAMPs that contribute to basal inflammatory levels. Epithelial cells are known to promote immune cell function and this interaction is crucial for mediating the change from tolerance to inflammation however little is known about this interaction in vivo. Cells sense DAMPs through a wide variety of receptors, expressed either in the membrane, like the P2X7 Receptor (P2X7R) or in the cytosol, such as the members of the NLR family (e.g. NLRP3, NLRP1). In immune cells, activation of these receptors leads to the assembly of the inflammasome, a molecular complex formed by an NLR, caspase-1 and the adaptor protein ASC, which acts as a platform for the activation of caspase-1 and the consequent secretion of the pro-inflammatory cytokines interleukin-1beta (IL-1 beta) and IL-18. However, our exciting new data suggest that epithelial cells do not respond in the same way to DAMPs as immune cells and P2X7R signalling preferentially triggers a chemokine response. The overall aim of this proposal is to determine the molecular mechanisms that regulate damage receptor signalling in epithelial and immune cells (DC) in the gut. This will be achieved using in vivo as well as in vitro approaches and techniques such as flow cytometry, western-blot, ELISA, qPCR, cell culture, gene editing CRISPR/CAs9 technology or live-cell imaging.
This project has an inter-departmental supervision that embodies a multi-disciplinary approach. Specifically this project will use in vivo, ex-vivo and in vitro approaches to decipher new mechanisms by which DAMPs contribute to dysregulation of gut homeostasis. This project will also develop data analytical skills to manage and interpret biological data through data handling, statistics and experimental design.