Regulation of the Release of Inflammatory Mediators From Lung Macrophages.
Condition: COPD; Chronic Bronchitis; Emphysema
MeSH terms: Bronchitis; Bronchitis, Chronic; Emphysema
Study type: Observational

Summary: 
      The aim of this study is to investigate the mechanisms whereby specific white cells called
      macrophages found in the lung release inflammatory mediators or chemicals together with
      enzymes that destroy the surrounding lung tissue. The hypothesis is that in diseases such as
      chronic obstructive pulmonary disease (COPD), lung macrophages release either more or
      different types of inflammatory mediators and/or destructive enzymes compared to subjects
      without COPD. We will isolate macrophages from small pieces of lung parenchyma. These samples
      are derived from lobes resected for carcinoma of the lung. We would aim to examine the
      responses of tissue derived macrophages in three groups of subjects, namely (i) non-smoking
      controls (lung carcinoma as secondary metastasis), (ii) smokers without clinical or
      histological signs of COPD and (iii) smokers with COPD. The resected lung tissue will be cut
      into small pieces and washed in order to release the macrophages from the tissue. The
      macrophages will then be isolated from other cell types in the washings. We will then use
      these isolated cells in vitro to examine the cell surface receptors in order to compare these
      macrophage cells with macrophages reported from bronchoalveolar lavage and monocyte derived
      macrophage models. We will then examine inflammatory mediator synthesis and release following
      stimulation of these cells. We will also examine the regulation and release of enzymes known
      to damage lung tissue. Using these two models we will then examine the signal transduction
      pathways that lead to this activation of the macrophages and investigate the effects of novel
      therapeutic agents to inhibit inflammatory mediator and/or enzyme synthesis and release. The
      objective is to identify the mechanisms whereby macrophages respond to pro-inflammatory
      conditions seen in COPD with a view to identify novel targets for drug therapy.
    

Detailed description: 
      Chronic obstructive pulmonary disease (COPD) is the fifth leading cause of death in the UK
      and is the only common cause of death that is increasing. COPD is currently 6th in the global
      impact of diseases and is predicted to by the 3rd leading cause of death by 2020. In the UK
      for 2000-2001 the estimated cost of COPD related illness is estimated at ~£980 million of
      which pharmacotherapy accounts for 48% of expenditure. At present pharmacotherapy for COPD is
      purely symptomatic with no drugs currently available that can halt the relentless progression
      of this disease. Therefore, there is a need for improved therapy for the treatment of COPD.
      Cigarette smoking is the major risk factor in the development of COPD, yet for reasons
      unknown only ~15% of smokers develop this disease, suggesting there is an underlying genetic
      component.

      COPD encompasses chronic bronchitis, small airways disease and emphysema and is associated
      with increased inflammatory cells in the lung including neutrophils, macrophages and CD8+
      T-lymphocytes. This inflammatory infiltrate is thought to be responsible for all the
      pathophysiological features of COPD but the precise mechanisms underlying this inflammatory
      response are unknown.In particular the macrophage is thought to mediate all the
      pathophysiological features of this disease. To this end, macrophages will be isolated from
      lung parenchyma using discontinuous percoll gradients. The cells will then be cultured
      overnight prior to assessment of inflammatory mediator release. Cells will be stimulated by a
      variety of agents including but not exclusively LPS, IL-1beta or TNF-alpha. The release of
      inflammatory mediators into the cell culture media will be measured using ELISA techniques.
      Enzyme activity will also be measured in both the cells and the culture media. Cell surface
      expression of specific markers will be assessed using immunocytochemistry and FACS analysis.
      Function of macrophages will be assessed by measuring phagocytotic activity by FACS analysis
      and fluorimetry. Specific signal transduction pathways will be assessed by the use of
      specific pathway inhibitors and gene expression measured by real-time PCR. The effects of
      novel therapeutic agents will be tested on these outputs with the aim to identify novel
      therapies for COPD.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All subjects undergoing lung resection surgery
      
Biospecimen description: 
      protein samples have been retained
    
Keywords: macrophage; inflammation; COPD