Background: COPD is characterised by increased neutrophilic inflammation which further increases during exacerbations. Corticosteroids are currently one of the mainstays of treatment but they have limited effectiveness; there is a great need to develop new anti-inflammatory pharmacotherapies for use in COPD. Inhaled LPS has been used as a model of increased neutrophilic inflammation in healthy patients, smokers and asthmatics. Its use in patients with COPD as a model of exacerbations has not yet been evaluated. PI3 kinase is a vital intracellular enzyme, which upon activation leads to a number of cellular processes; the γ and δ isoforms of the enzyme are of particular importance in leucocyte migration, development and activation. There is increasing evidence for upregulation of this pathway in COPD.Aims: (1) To test the safety of the use of inhaled LPS in patients with COPD for use as a model of exacerbation and to investigate the systemic and airway inflammatory response in vivo. (2) To investigate the action of PI3 kinase enzyme inhibitors and dexamethasone in vitro on neutrophilic inflammation in COPD patients during the stable state and exacerbations. Methods: (1) 12 patients with mild to moderate COPD inhaled 5µg LPS; safety measurements and airway and systemic biomarkers were collected up to 24 hours post inhalation. (2) The effect of PI3 kinase enzyme inhibitors and dexamethasone on MMP-9 and ROS release from peripheral and airway neutrophils from stable COPD and exacerbations was examined in vitro. The effect of PI3 kinase enzyme inhibitors and dexamethasone on cytokine release from peripheral neutrophils from stable COPD patients was also investigated. Results: (1) Inhaled LPS (5µg) caused a significant fall in FEV1 and increase in sputum neutrophil numbers. There was an associated increase in systemic IL-6, CRP and CC-16, all with differing temporal patterns. No patients reported any significant symptoms. (2) PI3 kinase enzyme inhibitors significantly reduced MMP-9 and ROS release from airway and peripheral neutrophils from COPD patients in the stable state and during exacerbations; dexamethasone had minimal effect. Cytokine release from peripheral neutrophils from COPD patients in the stable state was also significantly inhibited by PI3 kinase enzyme inhibitors and dexamethasone. Conclusions: (1) Inhaled LPS in patients with COPD is a safe model to induce acute on chronic neutrophilic inflammation and therefore could be used as a model to study COPD exacerbations. (2) PI3 kinase enzyme inhibitors reduce COPD neutrophil MMP-9, ROS and cytokine release in vitro and are therefore are a promising new anti-inflammatory pharmacotherapy.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:647409 |
| Date | January 2015 |
| Creators | Gupta, Vandana |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/pharmacological-targeting-of-neutrophilic-airway-inflammation-in-copd(73df122b-f031-445e-a6a9-bbcc0039b6c6).html |
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