In alpha-1-antitrypsin deficiency (A1ATD) there is excess neutrophil elastase activity, resulting in proteolytic destruction of the lung parenchyma. I hypothesised that the peptide fragments of proteins present in the lung might be detectable in plasma by mass spectrometry and that they might be useful biomarkers of disease activity and treatment efficacy. Calcium ionophore, neutrophil elastase and proteinase 3 were added to plasma from patients with A1ATD to create an in vitro model of the destructive processes. MALDI-based peptide profiling of plasma from patients pre and post treatment with intravenous A1AT was undertaken and MS/MS performed to identify differences. Plasma was also depleted of abundant plasma proteins, labelled with isobaric tags and analysed by shotgun proteomics. The readily detectible components of the plasma proteome remained unchanged with intravenous A1AT. Addition of ionophore, elastase and proteinase 3 to patient blood generated predominantly fragments of fibrinogen. In patients treated with intravenous A1AT, fragments of A1AT increased significantly with treatment: - 2 of these were fragments of a short C-terminal segment of the A1AT protein and were also present in healthy subjects. The shotgun experiments did not identify any robust biomarkers and illustrate the challenging nature of plasma proteomics.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:715699 |
| Date | January 2017 |
| Creators | Stone, Helen Marie |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/7565/ |
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