The purpose of the study is to compare airway physiologic reactions to physical exercise in a cold air environment (-5°C, 60% relative humidity) between normal volunteers and subjects with mild/moderate asthma. For this purpose, the investigators intend to evaluate the effect of a cold air exercise test on the Forced Expiratory Volume in 1 second (FEV1), respiratory symptoms, functional airway integrity, local and systemic inflammation and on the airway microbiome. This study also features as an exploratory study for a subsequent interventional study in order to establish the feasibility of the cold air exercise protocol and to determine the extent of the effects in subjects with mild/moderate asthma.
It is already demonstrated that exercising during cold air exposure and at a high altitude may induce asthmatic symptoms, a variable degree of airway obstruction and increased neutrophilic airway inflammation in asthmatic patients. Therefore, in this project, the investigators want to evaluate the feasibility, of a shorter standardized "cold air exercise test" (a submaximal exercise challenge in a controlled cold air (-5°C, relative humidity 60%) environment) and to compare the respiratory physiologic reactions to physical exercise during cold exposure between healthy volunteers and asthmatic patients. For this purpose, they intend to evaluate the effect of a cold air exercise test on FEV1, respiratory symptoms, functional airway integrity, local and systemic inflammation and on the airway microbiome. This study features as an exploratory study for a subsequent interventional study, that will assess the protective effect of azithromycin versus placebo on the cold air exercise induced changes in patients with mild/moderate asthma (ALASCAIR2 study). The present preparatory study is needed to standardize the cold air exercise test in a controlled environment so that it would be possible to use it as challenge test in an interventional study and to identify the most appropriate design for such a study. The primary objective of this study is to compare the proportional change in FEV1, pre to post a 90 minutes submaximal exercise in a cold air environment between healthy volunteers versus mild/moderate asthmatics, calculated as a time-weighted average over the 30 minutes post-exposure. The primary endpoint is the change in FEV1, calculated as a time-weighted average over the 30 minutes after the cold exercise test. At each time point (pre-exposure, 5' post-exposure, and at 15, 25 and 35 minutes post-exposure), FEV1 (L) will be measured in triplicate. They want to evaluate whether the exercise test in a cold air environment produces respiratory symptoms (such as nasal discharge or obstruction, dyspnea, cough and/or mucus production, etc.), has an impact on airway integrity (nasal patency, airflow obstruction, lung ventilation inhomogeneity \& small airway dysfunction, bronchial hyperreactivity, cough reflex hypersensitivity), induces local or systemic inflammatory changes (biomarkers in nasal fluid, sputum and blood) or changes to the airway microbiome (in nasal fluid and sputum) in healthy volunteers and in mild/moderate asthmatics. The study group also want to compare the observed changes induced by the cold air exercise test between the healthy volunteers and the mild/moderate asthmatics. The secondary endpoints of this study include the observed changes in (respiratory) symptom score, Peak Nasal Inspiratory Flow (PNIF), Forced Vital Capacity (FVC), Forced Expiratory Flow (FEF25-75), Fraction of Exhaled Nitric Oxide (FeNO), histamine provocative concentration causing 20% drop in FEV1 (PC20), cough threshold C2 \& C5, sputum differential cell count, biomarkers in nasal fluid, sputum and blood, nasal and sputum microbial communities between the healthy volunteers and the mild/moderate asthmatics.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
45
Subjects will perform a submaximal 90 minutes exercise test in a controlled cold air environment (-5°C, 60% relative humidity) in a climate chamber with evaluation pre§/during\*/post§ of heart rate (HR)§\* and blood pressure (BP)§\*, spirometry§\*, PNIF§, FeNO§, electrocardiogram (ECG)§\*, body \& exhaled air temperature§\*, capsaicin cough threshold test§, histamine bronchial challenge test§, and sampling of nasal fluid§, induced sputum§, and venous blood§.
UZ Leuven Gasthuisberg
Leuven, Belgium
Change in Forced Expiratory Volume in 1 seconds (FEV1)
Change in FEV1, calculated as a time-weighted average over the 35 minutes after the cold air exercise test and 24 hours and 1 week post-exposure. A maximal fall of 10% will be considered as positive response
Time frame: pre-, 5, 15, 25 and 35 minutes, 24 hours and 1 week post-exposure
Changes in asthma control
Asthma control will be determined using the Asthma Control Questionnaire (ACQ-6), including 6 questions. Each question will be scored from 0-6 and added together. This final score will be divided by the number of questions. If ACQ-6 \< 0.75 = controlled asthma, ACQ-6 from 0.75-1.5 = partly controlled asthma and ACQ-6 \> 1.5 = uncontrolled asthma.
Time frame: Pre-exposure and immediately, 24 hours and 1 week post-exposure
Changes in respiratory symptom score
The degree of dyspnea will be determined using Borg scale. This Borg scale is 0 to 10 rated scale. With 0 no dyspnea and 10 complete dyspnea.
Time frame: Pre-exposure and immediately, 24 hours and 1 week post-exposure
Cough hypersensitivity
Cough hypersensitivity (Capsaicin cough threshold) will be measured using a capsaicin challenge test. The concentrations (µmol/l) which provokes 2 coughs (C2) and 10 coughs (C10) will be recorded and will be compared before and after cold air exposure.
Time frame: Pre-exposure and 24 hours and 1 week post-exposure
Bronchial hyperreactivity
Bronchial hyperreactivity will be measured using a histamine provocation. Bronchial hyperreactivity will be confirmed when there is a drop of 20% in FEV1 post histamine provocation (PC20).
Time frame: Pre-exposure and 1 week post-exposure
Nasal hyperreactivity
Nasal hyperreactivity will be measured using a PNIF measurement. Nasal hyperreactivity will be confirmed when there is a drop of 20% in PNIF.
Time frame: Pre-exposure and immediately and 24 hours post-exposure
Airway inflammation
Bronchial airway inflammation. Differential cell count will be performed on sputum samples, determining eosinophilic (\>3% eosinophils, \<61% neutrophils), neutrophilic (\<3% eosinophils and \>61% neutrophils), pauci-granulocytic (\<3% eosinophils and \<61% neutrophils) and mixed granulocytic airway inflammation (\>3% eosinophils and \>61% neutrophils).
Time frame: Pre-exposure and 24 hours and 1 week post-exposure
Cytokine pattern in the airways
Cytokines concentrations (pg/ml) will also be determined in sputum supernatant using a U-plex assay.
Time frame: Pre-exposure and 24 hours and 1 week post-exposure
Biomarkers for airway inflammation
FeNO will be used as biomarker for eosinophilic airway inflammation. FeNO \< 25 ppb = eosinophilic inflammation less likely, FeNO between 25 and 50 ppm = need further interpretation with additional clinical information, FeNO \> 50 ppm = indication of eosinophilic airway inflammation (according to the American Thoracic Society guidelines)
Time frame: Pre-exposure and 24 hours and 1 week post-exposure
Nasal inflammation
Cytokine concentrations (pg/ml) will be determined in the nasal fluid as biomarkers for nasal inflammation
Time frame: Pre-exposure and immediately and 24 hours post-exposure
Systemic inflammation
The degree of system inflammation will be determined via differential blood cell count.
Time frame: Pre-exposure and immediately, 24 hours and 1 week post-exposure
Biomarkers for systemic inflammation
The degree of system inflammation will be determined via C-reactive protein (CRP) levels. Normal values for CRP are considered \< 10 mg/ml.
Time frame: Pre-exposure and immediately, 24 hours and 1 week post-exposure
Changes in microbiome in lung and nose
The presence of 22 common respiratory viruses, 5 bacteria and 1 fungi will be determined using qualitative reverse transcription polymerase chain reaction (qRT-PCR) in sputum and nasal fluid. Pre and post-exposure microbiome patterns will be compared.
Time frame: Pre-exposure and 1 week post-exposure
Evaluation of the heart rate pattern
Cardiovascular health will be evaluated by determining the heart rate pattern using ECG. Deviation from a normal ECG pattern will be recorded.
Time frame: Pre-exposure and during the 90 minutes cold air exposure
Determining the exercise capacity
Exercise capacity will be checked. In a single test pre-exposure, the aerobic heart rate zone, anaerobic heart rate zone and maximal oxygen volume uptake (VO2max) heart rate zone will be evaluated to determine the exercise capacity
Time frame: Pre-exposure
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