Leukocyte Function in Asthma and COPD
Condition: Asthma; COPD; Emphysema; Chronic Bronchitis
MeSH terms: Bronchitis; Bronchitis, Chronic; Asthma; Emphysema
Study type: Observational

Summary: 
      The aim of this study is to examine the inflammatory mechanisms involved in the pathogenesis
      of inflammatory lung disease, in particular to compare the inflammatory profile seen in
      asthma and COPD. Evidence for inflammation in asthma and COPD is based on the finding of
      increased numbers of macrophages and neutrophils in the lungs and respiratory secretions of
      these patients. The inflammatory cells produce proteases, as well as, reactive oxidant
      species resulting in a protease/anti-protease imbalance which favours lung destruction. The
      aim is to examine the inflammatory mediators released by inflammatory cells (such as,
      macrophages and lymphocytes) in order to determine whether there are differences between
      non-smoking subjects, smoking subjects and patients with asthma or COPD. Monocytes are
      precursors of alveolar macrophages, and both monocytes and neutrophils are recruited to the
      lung from the blood via the action of specific chemoattractants. We have evidence that in
      inflammation there are higher levels of these chemoattractants. Therefore these cells might
      also demonstrate the same changes seen in alveolar macrophages from these patients.

      We also aim to assess the role of the macrophage precursor (monocyte) and neutrophils in the
      blood. We will also assess lymphocyte/monocyte interaction. We will do this as the lymphocyte
      may be involved in the initial recruitment of inflammatory cells. We will also assess the
      role of cytokines involved with monocyte/macrophage/neutrophil migration in induced sputum as
      well as the role of induced sputum in the migration of monocytes and neutrophils into the
      lung. Our aim is to link the initial changes in blood to the changes causing disease in the
      lungs. We aim to examine cellular responses in four groups of subjects, namely (i)
      non-smoking controls, (ii) smokers without clinical evidence of COPD or asthma, (iii) smokers
      with COPD (iv) asthmatic patients.
    

Detailed description: 
      Overall subjects will be characterised into one of four groups: normal non-smoking subjects,
      healthy smokers, patients with asthma and patients with COPD. Subjects will have had to
      fulfil inclusion and exclusion criteria, and give written consent.

      Recruitment Methods. Volunteer subjects (healthy non-smokers and healthy smokers) will be
      recruited from within the National Heart and Lung Institute. Volunteers will be recruited via
      advertising using ethically approved advertisements. Asthmatic and COPD patients will be
      recruited from the outpatient clinic at The Royal Brompton Hospital. At the screening visit,
      the diagnosis of asthma or COPD will be confirmed from the clinical case notes. If the
      patient is a volunteer, they will undergo a full history and examination, spirometry. Each
      subject will attend on one study visit only. At the first visit a number of investigations
      will be undertaken including, spirometry with reversibility (400 microg ventolin via metered
      dose inhaler if initial spirometry shows an obstructive picture to exclude asthmatics), and
      sputum induction. In addition, 50ml of venous blood will be taken.

      More specifically, the following interventions will be undertaken by each subject

        1. Medical History and Physical Examination A full medical history and physical examination
           (including height and weight) will be performed on the initial screening visit, in
           addition to that recorded in the clinical case notes.

        2. Respiratory Assessments Forced Expiratory Volume per second (FEVI) will be measured
           using a dry wedge spirometer (Vitalograph, Buckingham, UK) and expressed as a percent of
           predicted value. Subjects will be trained in the use of the apparatus before beginning
           the study. The baseline value at each visit will be measured after at least fifteen
           minutes of quiet rest, and will be taken as the highest of three readings made at one
           minute intervals. 400 microg ventolin administered via a metered dose inhaler will be
           given if initial spirometry shows an obstructive picture (FEV1 <80% predicted, FEV1
           /FVC<70%) in order to distinguish between the presence of asthma or COPD.

        3. Sputum Induction Sputum induction will be performed in the Asthma Laboratory. The
           subject will inhale 3.5% saline at room temperature, nebulised via a De Vilbiss 99
           Ultrasonic nebuliser set, at maximum output using a mouthpiece. After five minutes the
           subject will rinse his/her mouth thoroughly with water, and will be asked to cough
           deeply and expectorate sputum into a pot. Samples from this first five minute collection
           are discarded. This procedure will continue for a further ten minutes, and the resulting
           sample will be collected in a polypropylene pot.

           It is important to explain to the subject that the aim is to obtain sputum, and that
           saliva should be disposed of by spitting into a bowl which is later discarded.

           In the case of any chest discomfort or shortness of breath, the procedure is stopped and
           spirometry is repeated. If the FEV1 has fallen by 10% of the predicted value, the
           subject can rest until the FEV1 has returned to the baseline value or the procedure can
           be terminated.

           Sputum samples will be analysed for differential and absolute cell counts (eosinophils,
           neutrophils, macrophages, lymphocytes, and columnar epithelial cells). Sputum
           supernatants will be assayed for TNF-alpha, IL-8, interferon-gamma, and other cytokine
           levels.

           Immunohistochemistry will be performed on the induced sputum samples to identify the
           cellular localisation of factors involved with leukocyte function.

           Cytospin preparations will be made for differential cell counts and the soluble fraction
           will be used for cytokine assays.

        4. Venous Blood Sampling Fifty (50) millilitres of blood shall be venesected at the study
           visit. We will investigate factors involved in leukocyte function and chemotaxis. We
           will also assess cellular distributions of receptors thought to be important in
           regulation by using FACS analysis.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Four groups of subjects were recruited: patients with COPD (cigarette smokers), diagnosed
        according to current standard criteria, patients with asthma (non-smokers), diagnosed
        according to current standard criteria, including a personal history of asthma, current
        smokers without airways obstruction (FEV1480% predicted) and non-smoking control subjects
        without lung disease
      
Biospecimen description: 
      sputum
    
Keywords: sputum; macrophage; neutrophil