Allergen Challenge for Evoked Phenotypes in Asthma (the ACE Study)

This protocol outlines a single-site mechanistic study aiming to investigate long RNAs differentially expressed in the airway epithelium of asthma patients both at baseline and in response to segmental airway allergen challenges. Over approximately 14 days, the study spanned three visits: Visit 1: Comprehensive characterization of participants, encompassing lung function testing, methacholine challenge testing, and allergen skin prick testing. Visit 2: Participants underwent bronchoscopy wherein three procedures were performed a. Epithelial brushings were performed in a segmental airway (baseline sample) b. Diluent (inactive control) was instilled into another segmental airway c. A small dose of allergen was administered into a third segmental airway using standardized cat or dust mite allergen extracts. Visit 3 (24 hours or 7 days post Visit 2): Another bronchoscopy was carried out to collect epithelial brushings in the diluent challenged and allergen challenged segments The collected epithelial brush samples underwent analysis for mRNA expression in the epithelial brushings. The study successfully incorporated a total of 23 subjects, which included 18 asthmatics (with stable or well-controlled conditions), 2 allergic non-asthmatics, and 3 non-allergic non-asthmatics. Overall design: This was a single-site, mechanistic study investigating the differential expression of long RNAs in the airway epithelium of asthma patients before and after allergen challenges. The study spanned approximately 14 days and consisted of three visits. Procedures include lung function tests, methacholine challenge tests, allergen skin prick tests, and bronchoscopies with segmental allergen administration. The allergens used were either cat or dust-mite standardized allergen extracts. The third visit involved a bronchoscopy to gather epithelial brushings, which were then analyzed to measure mRNA (long RNA) expression. The study cohort comprised 23 subjects, segmented into 18 asthmatics with stable or well-controlled asthma, 2 allergic non-asthmatics, and 3 non-allergic non-asthmatics.