T Cell Effector and Regulatory Mechanisms in Asthma (MGH-001)
The specific hypothesis for this study is that there are fundamental differences in T effector and T regulatory cell responses in the lung to allergens in allergic asthma (AA) when compared to allergic nonasthmatics (ANA) that account for the difference in clinical responses. We will address this by comparing T cell responses in AA versus ANA subjects. These experiments will correlate T cell responses with measures of airway physiology using state-of-the art lung imaging and examine mechanisms controlling T cell activation in the airways of AA and the function of airway T regulatory cells during AA.
Biological: Allergen Challenge
Procedure: PET-CT imaging(13NN perfusion/ventilation, 18FDG inflammation, and CT imaging)
|Study Design:||Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
|Official Title:||T Cell Effector and Regulatory Mechanisms in Asthma|
- Differences in airway physiology and airway constriction [ Time Frame: 24 hours ] [ Designated as safety issue: No ]The primary endpoints are differences in airway physiology and airway constriction following segmental allergen challenge (SAC) in AA and ANA subjects using positron emission tomography (PET) in combination with high-resolution computed tomography (HRCT)
- Differences in BAL inflammatory mediator release [ Time Frame: 24 hours ] [ Designated as safety issue: No ]We will assess each BAL for inflammation and inflammatory mediator release. A pre-challenge BAL is obtained to insure the subject does not have baseline inflammation prior to the allergen challenge. The diluent challenged segment is used to control for effects of bronchoscopy and instillation of fluid in the lung. Analysis of the allergen challenged segment is done to confirm that allergen exposure led to airway inflammation, and allows us to correlate changes in airway physiology to inflammation in the allergen exposed segment.
- Differences in cellular analysis of BAL [ Time Frame: 24 hours ] [ Designated as safety issue: No ]A differential is calculated for each sample by counting at least 200 cells using morphology and staining characteristics to separate them into macrophages, lymphocytes, eosinophils, and neutrophils, allowing us to calculate the number and percentage of each cell type in the BAL. The cells are also stained for a panel of cell surface markers and intracytoplasmic proteins and analyzed by flow cytometry. This analysis will allow us to ensure that each subject responded to allergen challenge response with appropriate eosinophil and T cell recruitment into the BAL.
- Differences in BAL inflammatory protein levels [ Time Frame: 24 hours ] [ Designated as safety issue: No ]BAL fluid will be concentrated 10-fold using a Centricon filter (Millipore) with a 3,000 MW cutoff. We have found that assaying for cytokines is more reliable when the BAL is concentrated 10-fold since BAL is diluted ~100-fold by the procedure (70) Concentrations of a panel of 42 different cytokines, chemokines, and growth factors are measured using a LINCOplex human cytokine-chemokine kit as per manufacturer's guidelines (Millipore) and read on a Luminex 100 (Luminex Corporation). Results are analyzed using Beadview software (UpstateCell Signaling Solutions).
|Study Start Date:||September 2012|
|Estimated Study Completion Date:||August 2020|
|Estimated Primary Completion Date:||August 2016 (Final data collection date for primary outcome measure)|
Experimental: Allergic asthmatic, allergic nonasthmatic
Adults who are allergic asthmatics or allergic non-asthmatics will receive segmental allergen challenge to the lung
Biological: Allergen Challenge
On the day of the first bronchoscopy,BAL will first be performed in the lingula without instillation of diluent or allergen.Then, a 2-ml aliquot of isotonic diluent is instilled into the right upper lobe. Then, the procedure will be repeated in the right middle lobe with instillation of 2-ml of standardized cat or mite allergen solution.A "test dose" concentration of allergen is administered first consisting of 2 ml of allergen at 1/10th the threshold concentration.If on visual inspection through the bronchoscope, there is no evidence of mucosal inflammation, a second segmental allergen challenge will be done in the right middle lobe using 2-ml of full-dose allergen at the threshold concentration.This dose will be predetermined by quantitative skin prick testing.A second bronchoscopy is performed 24 hours after delivery of allergen extract and diluent.
Other Names:Procedure: PET-CT imaging(13NN perfusion/ventilation, 18FDG inflammation, and CT imaging)
Imaging is first performed the evening prior to the 1st bronchoscopy.An IV catheter is placed.An attenuation correction is performed to remove image distortion using a chest CT volumetric scan.Subjects are instructed to exhale to the same mean lung volume of the CT scan and hold their breath for 20sec.Simultaneous with apnea,13NNsaline is injected IV and a series of PET scans is acquired.Then subjects resume breathing, matching their previous respiratory rate and tidal volume.After 3 min,within an interval of 1 min,spirometry and 2 deep inhalations are performed,followed by 1 min of washout. For the second imaging visit, which will occur 24 hour later, the imaging sequence will be repeated as described above, but will also include 18FDG infusion.At least 30 minutes after the 13NN injection,10mCi of 18FDG is infused. Then, images are collected over a 75 minutes.Venous blood is sampled at 5 different time points over a 40-45 minute time window to determine plasma radioactive levels.
Despite advances in medications, allergic diseases, including allergic asthma, continue to rise in prevalence(2). For this reason, there is a need for a better understanding of the mechanisms of allergic diseases and novel insights into modulating allergic inflammation. CD4+ Th2-type lymphocytes seems to be central to the pathogenesis of allergic disease, as the levels of these cells and Th2 cytokines (IL-4, IL-5 and IL-13) are elevated in the airways of allergic asthma patients (3-6). The unifying hypothesis of this project is that understanding the mechanisms that determine the critical balance of effector and regulatory allergen-specific T cell activity in asthma will lead to new approaches for inducing allergen-specific tolerance and new therapeutic strategies for asthma.
|Contact: Daniel L Hamilos, M.D.||email@example.com|
|Contact: Benjamin D Medoff, M.D.||firstname.lastname@example.org|
|United States, Massachusetts|
|Massachusetts General Hospital||Recruiting|
|Boston, Massachusetts, United States, 02114|
|Contact: Lauren E Tracy, B.S. 617-643-2262 email@example.com|
|Contact: Alisa K Brennan, B.S. 617-726-6376 firstname.lastname@example.org|
|Sub-Investigator: Daniel L Hamilos, MD|
|Sub-Investigator: Benjamin D Medoff, MD|
|Sub-Investigator: Robert S Harris, MD|
|Principal Investigator: Andrew D Luster, M.D., Ph.D.|
|Principal Investigator:||Andrew D Luster, M.D., Ph.D.||Massachusetts General Hospital|