Genetic Susceptibility TO Ozone-induced Airway Inflammation in Humans
Condition: Healthy Control
MeSH terms: Genetic Predisposition to Disease
Study type: Interventional

Summary: 
      The principal purpose of this study is to identify hyper-responsive, responsive and
      non-responsive groups of healthy human subjects based on their airway neutrophilic response
      to ozone exposure, and to perform micro-array analyses on DNA collected from recovered airway
      cells to explore possible differences in gene expression profiles between the three groups
    

Detailed description: 
      Sputum assessment day: Subjects meeting the required health status following the medical
      screening will be provided with a verbal and written description of all experimental
      procedures and possible risks involved in their participation. All subjects will be required
      to provide written informed consent to participate in the study. The ability of subjects to
      produce adequate induced sputum samples will also be determined. Therefore the subjects will
      be asked to produce sputum following inhalation of hypertonic saline (3, 4 and 5%). Subjects
      should be able to produce at least 50 mg of sputum (selected plug) per sample. Each sputum
      sample must contain a total cell count of at least 100,000 cells, a differential cell count
      containing less than 40% squamous epithelial cells, and cell viability of at least 50%, thus
      minimizing variability in cell recovery and squamous cell contamination. Subjects who are
      effective sputum producers will then be scheduled for a training session. Subjects may still
      be excluded from the study if unable to perform adequate pulmonary function tests.

      Training session: Training session will occur no less than 2 days prior to exposure

        -  Lung function tests, including spirometry and plethysmography (body box measurements).

        -  Introduction to the ozone exposure chamber.

        -  Instruction on how to use the treadmill, including a minute ventilation measurement to
           reach the level of exercise required for the study.

        -  Nitric oxide measurement - this measures the amount of nitric oxide (NO) present in
           expired air. An increased concentration of NO in exhaled air may be found in normal
           persons with acute inflammation during upper respiratory tract infections and in
           association with symptoms in patients with allergic rhinitis. Thus, measurement of the
           concentration of NO in expired air may be useful as an indirect assessment of airway
           inflammation. Lung production of NO will be measured by collection of a sample of
           exhaled gas. Nasal production of NO will be measured directly by connecting a NO
           analyzer sampling line to one nostril with the other nostril open to ambient air. During
           the nasal measurement the subject will exhale through a cardboard, disposable tube with
           a resistance in order to close the palate and prevent contamination of the nasal sample
           with. The entire procedure should be completed in less than 15 minutes.

      Exposure and testing protocol: Upon arrival at the laboratory, subjects' clinical health
      status will be ascertained by medical personnel, including base line heart rate, blood
      pressure, evaluation of respiratory symptoms (breath sounds) and general health. All female
      subjects will be required to provide a menstrual cycle history and a urine sample will be
      required for pregnancy testing. Each pregnancy test will be considered valid for 7 days.
      Testing will be postponed if a subject exceeds previously established limits.

      The 0.4 ppm ozone exposure will be conducted in an ozone exposure chamber. Each subject will
      be exposed to ozone for 2 hours. During the exposure, subjects will perform four 15 minute
      bouts of moderate exercise (minute ventilation or VE = 30 40 L/min) on a treadmill, each
      separated by 15 minutes of seated rest. Before and after exposure, lung function and breath
      sounds will be assessed for any signs of bronchial constriction. Venipuncture (as noted
      above) will occur prior to exposure. Measurements of cardiorespiratory performance will be
      obtained during each exercise period.

      Approximately 4-6 hours following ozone exposure, venipuncture will occur. Subjects will
      perform the sputum induction procedures described above with nebulized inhaled hypertonic
      saline (3, 4 and 5%). The subject will remain under medical supervision until pulmonary
      function (spirometry) returns to within 5% of pre-exposure baseline values before leaving the
      laboratory. Approximately 24 hours after the ozone exposure, subjects will return to the
      laboratory for lung function testing and sputum induction, in addition to a venous blood
      sample.

      At each time point (pre and post exposure, and 24 hours post exposure), blood will be drawn
      from the vein in forearm into clinical lab tubes. During one of these blood draws the
      additional 5ml will be drawn for genotyping. Plasma will be separated from 4 ml and frozen at
      70 degrees C for future analysis of mediators of interest, such as cytokines, as well as
      other systemic effects of ozone. The remaining blood will be assessed by whole blood assays
      for markers of inflammatory and immune activation (CD11b, CD14, CD64, CD16, HLA-DR, CD45,
      CD3, CD80, CD86) and function (phagocytosis and oxidative burst) by two colour flow
      cytometry. RNA will be extracted from sputum inflammatory cells for microarray analysis,.

      During the course of participation all subjects will be required to abstain from; ingestion
      of Vitamins C and E, aspirin or any other anti-inflammatory medication, exposure to cigarette
      smoke or other irritants. In addition, subjects will be asked to have nothing by mouth for 2
      hours before sputum induction. They will be asked to arrive in the research lab NPO x 2 hours
      on training day and post exposure day, and will have lunch on exposure day at a time that
      will allow for the 2 hour NPO requirement.
    

Intervention name(s): ozone
Intervention type(s): Other
Intervention description(s): 0.4 ppm ozone for 2 hours
Other intervention name(s): O3
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: ozone