The Bronchiectasis- rhinosinusitis association is characterized by sputum eosinophilia

Background: Bronchiectasis (BE) is commonly associated with chronic rhinosinusitis (CRS), an eosinophilic disorder. Eosinophilic BE has recently been described. We explored airway inflammation in people with BE+CRS. Methods: People with idiopathic or post-infectious BE were assessed for concomitant CRS by history, endoscopy, and sinus CT. We excluded people with asthma, PCD, and smokers. After a 7-day washout from ICS we assessed clinical features (dyspnea, Sino-Nasal Outcome Test (SNOT-22), sputum production, past exacerbations (PE)), sputum and blood cell count, nasal and FENO, methacholine test, skin testing and total and specific IgE, cytokines in sputum and serum by ELISA, and 16SrRNA in sputum and nasal brushing. Results: We included 22 people with CRS (BE+CRS) and 17 without CRS (BE). Sex, age, BMI, lung function, Reiff score, BSI, and past PE were similar. Median (IQR) sputum eosinophil fractions were 0 (0-1.5) in BE, and 3(1-12) in BE+CRS (p=0.012). 61.9% of BE+CRS vs. 23.5% of BE had ≥2% sputum eosinophils (p=0.018), with correlation between sputum and blood eosinophils (ROC AUC. 670 [.51-.853]). Methacholine tests were negative in 85.7% BE and 85.2% BE+CRS (p>0.99). Specific IgE and skin testing were mostly negative and similar. Nasal NO was decreased in CRS+BE (481±397 vs. 1455±789, p=0.003), and FENO was similar. We found a strong correlation between SNOT-22 and MMRC dyspnea scores (R=0.56, p=0.000). Serum TSLP was elevated in BE+CRS vs. BE (4.4 (12.5-29.2) vs. 1.65(.11-10.0)kIU), p=0.052. Microbiome analysis is under way. Conclusion: BE+CRS is associated with an eosinophilic, non-allergic airway inflammation. This has potential therapeutic implications such as ICS and biologic agents.