Glucocorticoid regulation of interleukin 8 expression in chronic obstructive pulmonary disease
Lead Research Organisation:
University of Manchester
Department Name: Medical and Human Sciences
Abstract
Chronic obstructive pulmonary disease (COPD) is an inflammatory lung condition and a major cause of deaths worldwide. Since it is an inflammatory disease antiinflamatory medication such as steroids should be effective. However steroids usually fail to improve the COPD disease course significantly. This clinically observed resistance to steroid treatment is likely to be important for understanding the basis of the disease itself, and also for the clinical management of patients.
We are, therefore, currently investigating steroid action in COPD. We are doing this by comparing inflammatory lung cells between COPD patients and healthy volunteers. Interleukin 8 is a critical signal for recruitment of inflammatory cells to the lung, and is expressed at high level in COPD. Interleukin 8 is typically inhibited by glucocorticoids; but this effect is lost in COPD, contributing to their lack of beneficial effect. We will discover why interleukin 8, in COPD, acquires resistance to glucocorticoid inhibition. This will indicate new approaches to COPD treatment.
We are, therefore, currently investigating steroid action in COPD. We are doing this by comparing inflammatory lung cells between COPD patients and healthy volunteers. Interleukin 8 is a critical signal for recruitment of inflammatory cells to the lung, and is expressed at high level in COPD. Interleukin 8 is typically inhibited by glucocorticoids; but this effect is lost in COPD, contributing to their lack of beneficial effect. We will discover why interleukin 8, in COPD, acquires resistance to glucocorticoid inhibition. This will indicate new approaches to COPD treatment.
Technical Summary
Background: Chronic obstructive pulmonary disease (COPD) is a major cause of premature death, and morbidity throughout the world. The disease is generally resistant to glucocorticoids (GC). Alveolar macrophages appear to have a central role, attracting neutrophils and lymphocytes. COPD encompasses many different phenotypes. A high sputum eosinophil count is associated with better glucocorticoid response therefore defining a particular disease phenotype. Interleukin 8 production by airway macrophages is constitutively high, and resistant to inhibition by GC, whereas peripheral blood derived macrophages respond to both stimulation with lipopolysaccharide (LPS), and inhibition with GC.
Aim: To define the basis for the constitutively high expression of IL-8.
Design: I will recruit patients with COPD, either with high sputum eosinophil counts or low eosinophil counts. Airway macrophages will be harvested at bronchoscopy, with airway mucosal biopsies.
Objective 1: I will define ex-vivo cytokine responses to stimulation with LPS, and inhibition with GC, p38 kinase or both. A limited immunohistochemical study will then be done using previously optimised antibodies to cells.
Objective 2: Using celltracker software and confocal microscopy I will measure expression, and activation of the glucocorticoid receptor (GR). I will also track p38 and NFkB. I will determine protein expression in conditions of LPS activation, p38 inhibition, GC treatment and inhibition with both p38 and GC.
Objective 3: Using a new form of chromatin immunoprecipitation. I will examine the IL8 gene architecture, and transcription factor binding. I will compare lung with peripheral blood derived cells, and will use the TNF gene, which is repressed by GC under the same conditions, as a further control.
Scientific and Medical Opportunities: I will define why IL8 is not repressed by GC therefore suggesting new therapeutic approaches. I will also be able to use p38 inhibitors, which are in early clinical trials, to investigate the role of this kinase in modulating GC action.
Aim: To define the basis for the constitutively high expression of IL-8.
Design: I will recruit patients with COPD, either with high sputum eosinophil counts or low eosinophil counts. Airway macrophages will be harvested at bronchoscopy, with airway mucosal biopsies.
Objective 1: I will define ex-vivo cytokine responses to stimulation with LPS, and inhibition with GC, p38 kinase or both. A limited immunohistochemical study will then be done using previously optimised antibodies to cells.
Objective 2: Using celltracker software and confocal microscopy I will measure expression, and activation of the glucocorticoid receptor (GR). I will also track p38 and NFkB. I will determine protein expression in conditions of LPS activation, p38 inhibition, GC treatment and inhibition with both p38 and GC.
Objective 3: Using a new form of chromatin immunoprecipitation. I will examine the IL8 gene architecture, and transcription factor binding. I will compare lung with peripheral blood derived cells, and will use the TNF gene, which is repressed by GC under the same conditions, as a further control.
Scientific and Medical Opportunities: I will define why IL8 is not repressed by GC therefore suggesting new therapeutic approaches. I will also be able to use p38 inhibitors, which are in early clinical trials, to investigate the role of this kinase in modulating GC action.