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Mitochondrial Damage-associated molecular patterns (mtDAMPs) are an emerging source of endogenous alarmins. N-formylated peptides bind members of the formyl-peptide receptor (FPR) family. From its original role in chemotaxis of immune cells towards sites of infection the part that this G-protein coupled receptor (GPCR) plays in the human body is expanding with expression evident in cells of non-phagocyte origin as well as neutrophils and macrophage. To investigate how FPR1 affects the development of pulmonary fibrosis the bleomycin acute injury in vivo model was employed as its pathogenesis shares features with Idiopathic pulmonary fibrosis (IPF). Transgenic mice lacking functional fpr1 displayed a reduced inflammatory profile and fibrotic phenotype at acute and end-stage endpoints respectively post-bleomycin instillation. In vivo models of fibrosis in different organs such as the liver and kidney there was not the same protective effect with deletion of fpr1 as with acute bleomycin lung injury mechanism. This in turn brought the pathogenesis of the in vivo models into question particularly due to the abundance of fpr1 expression on neutrophils, the first line of defense of the immune system. By depleting neutrophils prior to the bleomycin injury the nature of these myeloid cells in this lung fibrosis model and through evaluation of the inflammatory and fibrotic phases post-instillation it is evident that these cells play a major role in how the disease develops. Translation to the human disease (IPF) was a vital step to elucidate the true role of FPR1 in chronic fibrosis mechanisms. Expression was demonstrated by immunofluorescence in CD45+ leukocytes as well as in isolated fibroblasts. This was corroborated by mRNA levels in primary cultured cells when FPR1 expression was ‘primed’ by inflammatory stimuli such as lipopolysaccharide (LPS). With effects observed in a murine setting and also in primary tissue/cells the FPR1 effect may be microenvironment/neutrophil dependent.

Infectious bronchitis is a highly contagious respiratory disease that results in reduced egg production and can be fatal in young birds. It has recently been identified as the most economically detrimental disease to the poultry industry. It is caused by the gammacoronavirus infectious bronchitis virus (IBV), which is endemic in most countries worldwide. All viruses modulate cellular processes to establish themselves within the cell. The cellular PI3K/AKT signalling pathway is often modified by viruses and plays a crucial role in the regulation of many cellular processes. In this project the activation of the PI3K/AKT signalling pathway and downstream processes such as apoptosis, translation and macropinocytosis were investigated during IBV infection. Techniques such as western blotting, immunofluorescence, flow cytometry and protein expression were used to determine the effect of IBV infection on modulation of the signalling pathway, as well as the downstream cellular effects of the modulation. This study demonstrates that IBV requires an active PI3K/AKT pathway for efficient replication, and that infection with IBV induces phosphorylation of AKT in a PI3K-dependent manner in mammalian and avian cells. This activation occurs late during infection in mammalian cells. However, in avian cells activation occurs in a biphasic manner at both an early and late time point during infection. To summarise the findings, a model is presented to describe the role of the PI3K/AKT signalling pathway during IBV infection. This study highlights the importance of the PI3K/AKT signalling pathway during IBV infection and may be applied to other human and livestock coronaviruses for development of therapeutics or novel vaccines.

Much of the biology surrounding macrophage functional specificity has arisen through examining them during inflammation. However, tissue-specific triggers influence macrophage phenotype and function in health. The TAM family of receptor protein tyrosine kinases mediates the non-inflammatory removal of apoptotic cells by phagocytes through the bridging phosphatidylserine-binding molecules Gas6 or Protein S. We show that one such TAM receptor (Axl) is exclusively expressed on mouse airway macrophages, but not interstitial macrophages and other lung leukocytes, under homeostatic conditions and is constitutively ligated to Gas6. Axl expression is potently induced by GM-CSF expressed in the healthy and inflamed airway, and by type I interferon or TLR3 stimulation on human and mouse macrophages, indicating potential involvement of Axl in apoptotic cell removal under inflammatory conditions. Indeed, an absence of Axl does not cause sterile inflammation in health, but leads to exaggerated lung inflammatory disease upon influenza infection. The exacerbation of influenza infection was not due to inability to clear the viruses in Axl-/- mice, but was associated with enhanced weight loss, increased airway cellular infiltrates, and elevated nucleosome release indicative of secondary necrosis. These data imply that Axl allows specific identification of airway macrophages, and that its expression is critical for macrophage functional compartmentalisation in the airspaces or lung interstitium. We propose that this may be a critical feature to prevent excessive inflammation due to secondary necrosis of unefferocytosed apoptotic cells following inflammation.

Influenza causes substantial morbidity and mortality in some influenza sea- sons, especially among the elderly. Influenza seasons dominated by circula- tion of influenza A/H3N2 virus tend to result in more morbidity and mor- tality than seasons dominated by influenza A/H1N1 or influenza B viruses. Influenza viruses undergo constant mutation, called antigenic drift, which is largely driven by host immunity. It has been shown that antigenic drift in influenza A/H3N2 virus proceeds in a punctuated, as opposed to contin- uous, fashion. A cluster of antigenically similar influenza A/H3N2 viruses appears to remain dominant for between 1 and 8 influenza seasons before being supplanted by a new cluster. Influenza seasons when a new cluster becomes dominant may result in higher morbidity and mortality than other seasons. Influenza vaccine effectiveness varies between influenza seasons be- cause of the different subtypes in circulation and the degree of antigenic match between vaccine and circulating variants. In each influenza season in recent years, over 70% of the population of England & Wales aged > 65 has been vaccinated, though the impact of this high coverage on population level morbidity and mortality is unknown. Multivariate time series models were fitted to reports of laboratory confirmed influenza, sentinel general practi- tioner (GP) consultations for influenza-like-illness, and all deaths registered to underlying pneumonia or influenza in England & Wales from 1975/76 to 2004/05. The models successfully distinguish influenza - attributable GP consultations and deaths from GP consultations and deaths that would be expected in the absence of influenza. This distinction is made jointly by the laboratory reports and the non-laboratory confirmed surveillance data. It is not possible to use the multivariate time series models to quantify the average effect of the appearance of a new cluster of influenza A/H3N2 virus variants, or vaccine impact, on influenza - attributable morbidity or mortality in the data analyzed. Reasons for this are discus