Diesel Exhaust Induces Glucocorticoid Resistance

NCT ID: NCT03615742

Last Updated: 2024-07-24

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: PHASE4
• Total Enrollment: 30 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2018-12-01
• Study Completion Date: 2025-12-31

Brief Summary

The investigators are studying the effects of exposure to diesel exhaust on lung inflammation in the presence and absence of an inhaled corticosteroid. Although data is mixed, studies show that asthmatics have increased lung inflammation and worse symptoms during periods of higher air pollution despite taking their anti-inflammatory corticosteroid medication. One possible reason is that air pollution exposure may decrease the ability of corticosteroids to combat inflammation.

To test this volunteers will inhale either a placebo or a corticosteroid, before sitting in an exposure booth for 2 hours breathing either filtered air or diluted diesel exhaust. Samples will be collected before and after exposure to analyze the effects of budesonide and diesel exhaust exposure.

Detailed Description

1) Purpose Inhalation of air pollutants leads to both airway inflammation, with increased cytokine expression and inflammatory cell recruitment to the airways, and to airway hyperresponsiveness, which together contribute to airway resistance and breathing difficulties. Correlational data indicate that exposure to air pollution increases inhaled corticosteroids (ICS) use in asthmatics, suggesting that steroidal anti-inflammatory medications are suboptimally effective under these conditions. However, a major issue is that no study has yet been performed specifically to determine the effects of controlled diesel exhaust (DE) exposure on responses to ICS. Furthermore, investigators need better insight into mechanisms, including the effects of epigenetic modifications and polymorphisms in oxidative stress response genes, which remain under explored. Investigators anticipate that an improved understanding of air pollution-induced ICS hyporesponsiveness (reduced effectiveness) could underpin preventative guidelines, guide ICS usage in response to environmental exposures, and inform rational pharmaceutical development. Ultimately this could lead to fewer exacerbations in asthmatic and other susceptible populations.

Hypothesis:

Acute exposure to DE reduces ICS-inducible gene expression in vivo in asthmatics, in part through effects on epigenetic processes.

Justification:

Air pollution exposure correlates with increased use of ICS inhalers in asthmatics, suggesting that ICS offer less control during periods of higher air pollution. As genes induced by ICS are critical in reducing inflammatory messenger ribonucleic acid (mRNA) and protein expression, the investigators have chosen to focus on the effects of DE on ICS-inducible gene expression as our primary endpoint.

Research Method:

To test this the effects of air pollution exposure on a corticosteroid, volunteers will inhale either a placebo (inhaler containing no medication) or budesonide (1.6mg), before sitting in our exposure booth for 2 hours breathing either filtered air (as a control) or diluted diesel exhaust (standardized to 300µg/m³ of particulate matter with a diameter of 2.5 micrometers or less).

Volunteers will visit our lab four different times to be exposed to: 1) placebo & filtered air, 2) placebo & diesel exhaust, 3) corticosteroid and filtered air, and 4) corticosteroid and diesel exhaust. Investigators can then compare responses to each of these combinations of exposures.

Investigators will take blood samples before and after volunteers complete each of these exposures to track how they affect the body. Six hours after placebo or budesonide inhalation a research bronchoscopy will be performed during which a very thin flexible tube will be inserted through the mouth and down into lungs to collect samples from each volunteer.

Bronchoalveolar lavage, bronchial washes, bronchial brushes and tissue biopsies will be obtained for analysis of gene expression and epigenetic endpoints. Nasal lavage samples will also be collected to examine responses in the upper airways and blood and urine will be studied to examine systemic responses. Spirometry will be used to assess effects on airway function.

Conditions

Exposure to Pollution; Glucocorticoid Resistance

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: PREVENTION
• Blinding Strategy: TRIPLE

Study Groups

Placebo and Filtered Air

Volunteers will use an inhaler that does not contain any medication, before sitting in a booth and being exposed to high-efficiency particulate air (HEPA) filtered air for 2 hours.

Group Type: PLACEBO_COMPARATOR

Placebo

Intervention Type: OTHER

Inhalation of air through a Turbuhaler that contains no medication, as a control.

Filtered Air

Intervention Type: OTHER

Exposure to HEPA filtered air, as a control.

Budesonide and Filtered Air

Volunteers will inhale 1.6mg of budesonide before sitting in a booth and being exposed to HEPA filtered air for 2 hours.

Group Type: ACTIVE_COMPARATOR

Budesonide

Intervention Type: DRUG

1.6mg of budesonide from a Turbuhaler.

Filtered Air

Intervention Type: OTHER

Exposure to HEPA filtered air, as a control.

Placebo and Diesel Exhaust

Volunteers will use an inhaler that does not contain any medication, before sitting in a booth and being exposed to 300µg/m³ concentration of diesel exhaust for 2 hours.

Group Type: ACTIVE_COMPARATOR

Placebo

Intervention Type: OTHER

Inhalation of air through a Turbuhaler that contains no medication, as a control.

Diesel Exhaust

Intervention Type: OTHER

Diesel exhaust standardized to 300µg/m³ of particulate matter with a diameter of 2.5 micrometers or less (PM2.5).

Budesonide and Diesel Exhaust

Volunteers will inhale 1.6mg of budesonide before sitting in a booth and being exposed to 300µg/m³ concentration of diesel exhaust for 2 hours.

Group Type: EXPERIMENTAL

Budesonide

Intervention Type: DRUG

1.6mg of budesonide from a Turbuhaler.

Diesel Exhaust

Intervention Type: OTHER

Diesel exhaust standardized to 300µg/m³ of particulate matter with a diameter of 2.5 micrometers or less (PM2.5).

Interventions

Placebo

Inhalation of air through a Turbuhaler that contains no medication, as a control.

Intervention Type: OTHER

Budesonide

1.6mg of budesonide from a Turbuhaler.

Intervention Type: DRUG

Filtered Air

Exposure to HEPA filtered air, as a control.

Intervention Type: OTHER

Diesel Exhaust

Diesel exhaust standardized to 300µg/m³ of particulate matter with a diameter of 2.5 micrometers or less (PM2.5).

Intervention Type: OTHER

Other Intervention Names

Pulmicort; Traffic Related Air Pollution

Eligibility Criteria

Inclusion Criteria

1. Aged 19-49

2. Have physician-diagnosed asthma confirmed by the study physician examination, spirometry, methacholine challenge provocative concentration causing a 20% fall (PC20) of <16 mg/mL, and questionnaires during a screening visit

Exclusion Criteria

1. Smoking of any kind (0.5 pack-years ever, or any current) or use of vape/vaporizing devices

2. Regular anti-histamine, NSAID, corticosteroid or other controller medication use

3. Pregnancy or breastfeeding

4. Methacholine PC20 >16

5. Relevant cardiac condition or arrhythmia

6. Body mass index of >35

7. Currently participating in another study that may interfere with this study

8. Use of either inhaled or oral corticosteroids in preceding 6 months

9. Substantial comorbidities on study physician's examination or other concerns

10. Surgery scheduled before anticipated study completion

• Minimum Eligible Age: 19 Years
• Maximum Eligible Age: 49 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Canadian Institutes of Health Research (CIHR)

OTHER_GOV

Sponsor Role: collaborator

AllerGen NCE Inc.

INDUSTRY

Sponsor Role: collaborator

University of British Columbia

OTHER

Sponsor Role: lead

Responsible Party

Christopher Carlsten

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Chris Carlsten, MD

Role: PRINCIPAL_INVESTIGATOR

University of British Columbia

Christopher F Rider, PhD

Role: STUDY_DIRECTOR

University of British Columbia

Robert Newton, PhD

Role: STUDY_DIRECTOR

University of Calgary

Locations

University of British Columbia

Vancouver, British Columbia, Canada

Site Status: RECRUITING

Countries

Canada

Central Contacts

Parteek (PJ) Johal, BCS

Role: CONTACT

de.study@ubc.ca

6048755132

Agnes CY Yuen, BSc

Role: CONTACT

agnes.yuen@ubc.ca

6048754111 ext. 66455

Facility Contacts

Chris Carlsten, MD MPH

Role: primary

carlsten@mail.ubc.ca

604-875-4729

Ryan D Huff, MSc

Role: backup

digr.study@ubc.ca

604-875-5132

Other Identifiers

H17-01336

Identifier Type: -

Identifier Source: org_study_id