Investigating the regulation of neutrophil gene expression by intracellular signalling and micro RNAs

Neutrophils are innate immune cells that play an essential role in the first line host response to infection. However, inappropriate neutrophil activation in auto-immune disease drives the inflammatory response through secretion of cytokines and chemokines, and damages host tissue by degranulation of proteolytic enzymes (e.g. MMP8, elastase). Neutrophil production of reactive oxygen species (ROS) further damages host tissues, and the externalisation of post-translationally modified proteins and DNA in neutrophil extracellular traps (NETs) leads to the production of auto-antibodies e.g. auto-antibodies to cyclic citrullinated peptides (ACPA) in RA and dsDNA antibodies in SLE.

Neutrophil gene expression is altered during inflammation leading to altered and pathogenic cell function. We have carried out extensive transcriptomics analysis of in vitro and ex vivo activated neutrophils from a range of inflammatory auto-immune diseases. Our bioinformatics analysis predicts that altered cell signalling and expression of microRNAs are regulating gene expression in neutrophils. This project will combine bioinformatics analysis with laboratory experiments to investigate the regulation of neutrophil gene expression by cell signalling and microRNAs in different models of inflammation.

Our hypothesis is that altered neutrophil gene expression in inflammation is regulated by signalling factors, for example NET debris activating Toll-Like Receptors on neutrophils leading to expression of inflammatory genes. We also hypothesise that as yet unknown factors alter the expression of microRNAs, leading to altered gene expression and proinflammatory functions.

The objectives of this project will be to (i) perform bioinformatics analysis of RNAseq data to identify microRNAs that are differentially expressed in inflammatory neutrophils (ii) investigate the regulation of neutrophil gene expression and function in IMID by neutrophil signalling products including NETs, (iii) identify factors altering the expression of microRNAs in healthy and disease neutrophils.

We will combine bioinformatics analysis of RNAseq datasets with in vitro experiments using human neutrophils from healthy controls and people with auto-immune disease to measure altered gene and microRNA expression as well as the effect of the altered expression on neutrophil functions such as ROS production, NET release, apoptosis, phagocytosis and bacterial killing.

This work will advance our understanding of neutrophil physiology in inflammation and contribute to a program of research focussed on the development of therapeutic targeting of unwanted neutrophil activation in inflammation, inflammageing and auto-immune disease.