Air Pollution and Inhaled Corticosteroids in COPD

APIC will involve 48 volunteer participants (24 of each biological sex assigned at birth) with mild-to-moderate COPD where the researchers will look at what (if any) are the differences between breathing in fresh air (filtered air - FA) or polluted air (diesel exhaust - DE) while taking the drug (Inhaled corticosteroid - ICS) or not (no ICS), both in combination with two standard COPD medicines that make it easier to breath (a long-acting beta-agonist and a long-acting muscarinic antagonist). The participant will take an inhaled medication daily throughout the study. This study will use a controlled amount of diesel exhaust to model traffic-related air pollution (TRAP), a commonly encountered form of polluted air. Each participant will act as their own control, as they will experience all four combinations: 1) FA-ICS, 2) FA-no ICS, 3) DE-ICS, and 4) DE-no ICS. These combinations will be randomized in what researchers call a double-blinded crossover study, so that every participant will get these combinations in a different order. However, only the engineer on the team will be allowed to know which participant gets what. Blinding will prevent everyone else, including the participant, from being biased against the conditions and affecting outcomes based on this perception. The study will span over five months (approximately 121 days of active commitment), which includes ten in-person visits to a research office at the Vancouver General Hospital, for a total of approximately 40 hours. While the participant is on-site, the investigators will supervise a series of questionnaires, sample collection (blood, urine, bronchoscopy lung samples), and lung function tests. The investigators will evaluate multiple endpoints as detailed in the Outcome Measures section. For each applicable endpoint, the investigators will evaluate stratified analyses and effect modification by biological sex, participant age, gene score, and microbiomes. The investigators do not expect that the participant's responses to either the corticosteroid or diesel exhaust will be noticeable to them. Any responses that may occur will probably only be detectable through careful examination of their cells and tissues (e.g., blood, urine, bronchial samples). However, understanding the subtle changes that may occur could help reduce or prevent health problems associated with TRAP exposure in the future.