Mechanistic Study of Epithelial miRNAs and T-cell Recruitment Dynamics That Occur After Allergen Challenge in Patients With Asthma.
Trial Snapshot
- Phase
- Phase 2
- Status
- Completed
- Sponsor
- Enrollment
- 28
- Locations
- 1
- Primary Endpoint
- Difference in Expression of Epithelial miRNAs (in Read Counts) 24 Hours After Allergen-challenge as Compared to 24 Hours After Diluent Challenge in Participants With Allergic Asthma
Study Overview
Brief Summary
This protocol describes a single site mechanistic study to investigate microRNAs (miRNAs) that are differentially expressed in the airway epithelium of patients with asthma at baseline and in response to allergen challenge. We hypothesize that allergen exposure enhances airway smooth muscle contractility and epithelial cell mRNA/miRNA production as a consequence of locally increased T-cell derived cytokine production. The study will involve three visits over the course of approximately 14 days. At Visit 1, participants will be characterized in detail with lung function testing, methacholine challenge testing, and allergen skin prick testing. At Visit 2, participants will undergo bronchoscopy with segmental allergen administration of either cat or dust mite standardized allergen extract. At Visit 3 (either 24 hours later or 7 days later), bronchoscopy will be performed to collect airway samples including bronchoalveolar lavage (BAL), epithelial brushings and endobronchial biopsies. Sample analysis will include measurement of miRNA and mRNA expression in epithelial brushings (RNAseq and qPCR); analysis of cell surface markers on BAL cells and blood cells; and collection of endobronchial biopsies for immunostaining of immune cells localization, immunoblotting of smooth cell protein phosphorylation, analysis of mucin content and smooth muscle cell subculture. A total of 38 subjects (26 asthmatics with stable or well-controlled asthma, 6 allergic non-asthmatics and 6 non-allergic non-asthmatics) will complete the study.
Study Design
- Study Type
- Interventional
- Allocation
- Na
- Intervention Model
- Single Group
- Primary Purpose
- Basic Science
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 50 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Allergic/Non-Asthmatic subjects and Allergic/Asthmatic subjects
- •Inclusion Criteria:
- •Positive skin test to dust mite or cat allergen
- •Non-Allergic/Non-Asthmatic subjects
- •Inclusion Criteria:
- •Negative skin test to panel of 12 allergens, including dust mite and cat allergen
Exclusion Criteria
- •History of intubation for asthma exacerbation
- •Use of Xolair (omalizumab) within the last 6 months
- •Immunotherapy with cat or dust mite extract now or in the past 5 years
- •≥ 10 pack-years smoking or any smoking in the past year
- •Other lung diseases, such as sarcoidosis, bronchiectasis or active lung infection
- •History of dermatographia
- •History of anaphylaxis to cat allergen
- •Participation in another research study involving a drug or biologic during the past 30 days
- •Presence of past or current medical problems/other factors that may pose additional risks from participation or influence study results, as determined per study investigator
Arms & Interventions
Allergen challenge subjects
Intervention: Segmental airway allergen challenge
Three types of subjects are studied in this arm:
- Volunteers with neither asthma nor allergy (as established by skin prick testing); 2) Volunteers with allergy (as established by skin prick testing) but without asthma; and 3) Volunteers with both asthma and allergy (as established by skin prick testing)
Intervention: Spirometry (Diagnostic Test)
Allergen challenge subjects
Intervention: Segmental airway allergen challenge
Three types of subjects are studied in this arm:
- Volunteers with neither asthma nor allergy (as established by skin prick testing); 2) Volunteers with allergy (as established by skin prick testing) but without asthma; and 3) Volunteers with both asthma and allergy (as established by skin prick testing)
Intervention: Allergen skin prick test (Diagnostic Test)
Allergen challenge subjects
Intervention: Segmental airway allergen challenge
Three types of subjects are studied in this arm:
- Volunteers with neither asthma nor allergy (as established by skin prick testing); 2) Volunteers with allergy (as established by skin prick testing) but without asthma; and 3) Volunteers with both asthma and allergy (as established by skin prick testing)
Intervention: Segmental airway allergen challenge (Biological)
Allergen challenge subjects
Intervention: Segmental airway allergen challenge
Three types of subjects are studied in this arm:
- Volunteers with neither asthma nor allergy (as established by skin prick testing); 2) Volunteers with allergy (as established by skin prick testing) but without asthma; and 3) Volunteers with both asthma and allergy (as established by skin prick testing)
Intervention: Bronchoscopy (Procedure)
Allergen challenge subjects
Intervention: Segmental airway allergen challenge
Three types of subjects are studied in this arm:
- Volunteers with neither asthma nor allergy (as established by skin prick testing); 2) Volunteers with allergy (as established by skin prick testing) but without asthma; and 3) Volunteers with both asthma and allergy (as established by skin prick testing)
Intervention: Methacholine challenge test (Diagnostic Test)
Outcomes
Primary Outcomes
Difference in Expression of Epithelial miRNAs (in Read Counts) 24 Hours After Allergen-challenge as Compared to 24 Hours After Diluent Challenge in Participants With Allergic Asthma
Time Frame: 24 hours
For each participant with Allergic Asthma, a baseline airway epithelial brushing was performed, allergen was instilled into one segment of the lung, and diluent (control) was instilled into another segment. Both segments were brushed for epithelial cells 24 hours later. After processing brushes to RNA and generating RNA sequencing data, the RNA transcript read counts for each gene underwent variance stabilized log normalization. Then we built a regression model which estimated the difference in miRNA read count in the allergen challenged as compared to the baseline sample and the difference in miRNA read count in the diluent challenged segment as compared to baseline for each participant. The change from baseline read count for each miRNA in the allergen samples was compared to the change in the diluent samples and statistical significance was assessed using the unadjusted p-value(\<0.05). The direction of change does not have clinical significance; this was a mechanistic study.
Difference in Expression of Epithelial miRNAs (in Read Counts) 7 Days After Allergen-challenge as Compared to 7 Days After Diluent Challenge
Time Frame: 7 days
For each participant with Allergic Asthma, a baseline airway epithelial brushing was performed, allergen was instilled into one segment of the lung, and diluent (control) was instilled into another segment. Both segments were brushed for epithelial cells 7 days later. After processing the brushes to RNA and generating RNA sequencing data, the RNA transcript read counts for each gene underwent variance stabilized log normalization. Then we built a regression model which estimated the difference in miRNA read count in the allergen challenged as compared to the baseline sample and the difference in miRNA read count in the diluent challenged segment as compared to baseline for each participant. The change from baseline read count for each miRNA in the allergen samples was compared to the change in the diluent samples and statistical significance was assessed using the unadjusted p-value(\<0.05). The direction of change does not have clinical significance; this was a mechanistic study.
Secondary Outcomes
No secondary outcomes reported
Investigators
Prescott Woodruff
Professor of Medicine
University of California, San Francisco