REGULATION OF NEUTROPHIL GENE EXPRESSION IN INFLAMMATORY DISEASE & AGEING
The major theme of my research is investigating the role of neutrophils in the pathophysiology of inflammatory diseases such as rheumatoid arthritis (RA) and in ageing. Research projects are focussed on understanding the regulation of neutrophil gene expression, identification of neutrophil-derived molecular biomarkers of response to therapy, discovery of novel targets for the development of new therapies, and understanding the molecular effects of therapeutics (anti-TNF therapy, anti-IL17A therapy, JAK inhibitors) on neutrophil function in inflammatory disease. My research combines functional laboratory assays on freshly-isolated peripheral blood neutrophils from patients and healthy controls stimulated in vitro with relevant agonists, and RNA-Seq to understand the phenotype of inflammatory neutrophils. As an Arthritis Research UK Foundation Fellow at the University of Liverpool I made a significant contribution to the understanding of neutrophil gene expression during inflammation, including publishing the first RNA-seq analysis of primary human neutrophils, cells which are notoriously difficult to work with in vitro, including making two datasets available to the public (GSE40548, GSE70068). I also published the first analysis of neutrophils from RA patients using RNA-Seq, identifying signalling pathways that correlate with disease activity. My Career Development Fellowship allowed me to extend our understanding of neutrophil gene expression in rheumatoid arthritis using computational modelling. Recent funding has allowed me to extend my molecular study of RA neutrophils using quantitative proteomics and 1H NMR metabolomics.

Previous funding: Career Development Fellowship Versus Arthritis (personal fellowship), Illix R&D Ltd, Wellcome Trust ISSF, Lupus UK

REGULATION OF NEUTROPHIL EXTRACELLULAR TRAP FORMATION
Neutrophil extracellular traps (NETs) kill pathogens via the release of chromatin and anti-microbial granule enzymes in an extracellular mesh or “net”. NET release represents a novel form of cell death (NETosis), distinct from apoptosis and necrosis, that can be induced by inflammatory agents (LPS, TNFα, IFNα) and micro-organisms. During NETosis, ROS production and protein-arginine deiminase (PAD)-4 activation induces histone citrullination, chromatin disruption and disintegration of the nuclear membrane. Granule enzymes are released from membrane-bound organelles into the cytoplasm, whereupon they mix with histones and decondensed chromatin, before the protein-loaded DNA is released via disruptions in the cell membrane. NETs may also a source of autoantigens in autoimmune diseases such as systemic lupus erythematosus (SLE) where they contribute to organ damage and nephritis. Emerging evidence also implicates NETs in RA as a source of citrullinated neoepitopes that can lead to loss of immune tolerance and development of antibodies to citrullinated proteins (ACPA), a hallmark of severe RA. This new evidence creates new avenues for understanding the role of neutrophils in RA. Serum autoantibody profiles in SLE and RA are different: the former typically have high titres of anti-dsDNA and anti-nuclear protein antibodies, while the latter have high ACPA. This suggests that either the molecular properties of NETs produced in SLE and RA are different and expose distinct autoantigens, or the host immune response to NETs in SLE and RA is different. This project is combining quantitative proteomics and immune-fluorescent staining to determine the molecular properties of NETs in RA and SLE.

Current projects: Self-funded PhD studentship (Mrs Sarah Shirley, with Dr Jill Madine ISMIB),
Previous funding: Connect Immune Research partnership with the Lorna & Yuti Chernajovsky Biomedical Research Foundation (with Prof Pat Eyers).

NEUTROPHIL METABOLOMICS IN INFLAMMATION AND AGEING
Neutrophils are phagocytic innate immune cells that play essential roles in host defence, but are also implicated in inflammatory diseases such as rheumatoid arthritis (RA) where they contribute to systemic inflammation and joint damage. Transcriptomic analysis of neutrophils has revealed significant changes in gene expression in neutrophils activated in vitro by cytokines and in vivo during inflammation in RA. However, there are no reports on the global metabolomic changes that occur during neutrophil activation. We already know that cellular metabolism is key regulator of neutrophil energy production, activation and function under conditions of both homeostasis and inflammation. Fine-tuning of metabolism during an inflammatory response is key for the generation of small molecule metabolites such as ATP, NADPH, nucleotides and amino acids, which are required rapidly and in high abundance during cellular activation. Neutrophils rely heavily on glucose metabolism via glycolysis to fuel their energy requirements. The first intermediate of glycolysis, glucose 6-phosphate (G6P), fuels the pentose phosphate pathway (PPP), where NAPDH is produced to fuel NOX2 activity, ROS production, and NOX2-dependent NET formation. We are using 1H NMR spectrometry to investigate the intracellular changes in the neutrophil metabolome during in vitro and in vivo inflammation. In particular, we are interested in the changes to the metabolome which take place in RA patients during treatment with therapies such as JAK inhibitors.

Current funding:
Previous funding: PhD scholarship from Versus Arthritis and the Masonic Charitable Foundation, PhD scholarship on joint program with Chulalongkorn University and the University of Liverpool (Dr Grace Filbertine), Dunhill Medical Trust (Dr Genna Abdullah, PhD studentship).
All projects with Dr Marie Phelan.