Glucocorticoid Resistance in COPD: The Role of p38 MAPK

  • Kate Gaffey

    Student thesis: Phd


    Chronic Obstructive Pulmonary Disease (COPD) is a chronic, inflammatory condition, characterised by airflow limitation. The use of glucocorticoids (GC) as an anti-inflammatory treatment in COPD has limited clinical benefits, and as such, new treatments are needed. Identifying key pathways involved in the inflammatory response in COPD may enable the development of novel treatments. The aims of this thesis were to examine the steroid sensitivity of an in vitro mixed sputum culture cell model, comparing COPD cells to smoking and non-smoking controls, examine expression of the intracellular signalling molecule p38 Mitogen Activated Protein Kinase (MAPK) in COPD lungs compared with controls, examine the GC and p38 MAPK inhibitor and dual therapy sensitivity of a bronchial epithelial cell line and finally, to understand the mechanisms by which a p38 MAPK inhibitor in combination with a GC synergistically inhibit pro-inflammatory mediator production in a bronchial epithelial cell line. Dexamethasone inhibits mixed sputum cell pro-inflammatory mediator release, with no differences in sensitivity observed between COPD and control cells. Isolated sputum neutrophils demonstrate modest sensitivity to dexamethasone, which is in contrast to blood neutrophils. There are increased numbers of cells positive for activated p38 MAPK in COPD lungs compared with controls, specifically localised to follicular B and CD8+ T cells, bronchial epithelial cells and alveolar and sputum macrophages. Lung and sputum neutrophils are devoid of activated p38 MAPK, and a pharmacological p38 MAPK inhibitor has no effect on pro-inflammatory mediator production from these cells. This is in contrast to blood neutrophils, whereby p38 MAPK activation can be induced following LPS stimulation and in vitro cell culture, and pro-inflammatory mediator release is inhibited by a p38 MAPK inhibitor. Dexamethasone and birb 796 inhibit stimulated pro-inflammatory mediator release from a bronchial epithelial cell line in a dose-dependent manner. Sensitivity to either drug is dependent on stimuli and the pro-inflammatory mediator analysed. There is additive and synergistic inhibition of pro-inflammatory mediator production when combination therapy comprising dexamethasone and birb 796 is used compared with either drug alone. This may be due to Birb 796 enhancing dexamethasone-mediated nuclear translocation of the glucocorticoid receptor, which may enhance the GC-mediated anti-inflammatory effects. Combination therapy may therefore be a useful therapeutic in the treatment of COPD.
    Date of Award1 Aug 2013
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorSukh Singh (Supervisor) & David Ray (Supervisor)


    • COPD, inflammation, glucocorticoid resistance, p38 MAPK

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