Abstract
Patients with liver disease are susceptible to sepsis which is associated with poor outcomes and high mortality. The immunopathology includes a defective innate immune response to invading microbes and an exaggerated systemic inflammatory response. Neutrophils, potential effectors of this differential response, undergo priming leading to alterations in phagocytic capacity and oxidative burst (OB). Ammonia-induced osmotic stress and a circulating pro-inflammatory milieu mediated through phosphorylation of the p38-MAPK signalling pathway have been postulated to be critical events in the development of neutrophil dysfunction in liver disease. This longitudinal case-control study characterised neutrophil morphology, phenotype and function ex-vivo in patients with acute liver failure (ALF) and cirrhosis. The role of ammonia–induced osmotic stress in relation to the p38-MAPK pathway was explored.25 patients with ALF and 67 patients with cirrhosis were compared with healthy (HC) and sepsis controls (SC). Utilising flow cytometry, neutrophil phenotype was determined by surface CD16 and CD11b expression, phagocytosis quantified with FITC-labelled E.coli, OB pre/post-exposure to E.coli by 123-rhodamine fluorescence, chemotaxis by the number of cells migrating towards a fMLP concentration gradient and cell volume determined by forward scatter characteristics with confirmatory transmission electron microscopy. Plasma cytokine concentrations were determined using ELISA. Finally, neutrophil function assays were repeated after pre-incubation with p38-MAPK modulators and intracellular levels of total and phosphorylated p38- MAPK were determined. My data demonstrate that circulating neutrophils in ALF have impaired bactericidal function similar to that seen in severe sepsis. Neutrophil function indices are important biomarkers in ALF and may be implicated in the development of organ dysfunction and increased susceptibility to sepsis. Likewise, neutrophils in patients with cirrhosis are dysfunctional and predict the development of infection, organ dysfunction and survival at 90-days and 1-year. Neutrophil swelling correlates with peak arterial concentration and can be abrogated ex-vivo following incubation with the p38-MAPK agonist isoproterenol.
| Date of Award | 2016 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Yun Ma (Supervisor) & Debbie Shawcross (Supervisor) |