A comparative analyses of group 2 innate lymphoid cells in sputum from patients with non-asthmatic eosinophilic bronchitis and allergic asthma

<bold>Background:</bold> Non-asthmatic eosinophilic bronchitis (NAEB) is an airway disorder characterized by chronic cough and sputum eosinophilia in the absence of airway hyperresponsiveness. Group 2 innate lymphoid cells (ILC2) are increased in the sputum from NAEB compared to normal healthy controls and correlate with airway eosinophilia¹. We have reported that Neuromedin-U (NMU) via ligation of the cognate receptor, NMUR1 mediates rapid activation of ILC2 in asthma². <bold>Objective:</bold> To enumerate and perform phenotyping of airway ILC2 in chronic cough patients diagnosed with NAEB. <bold>Methods:</bold> Patients with chronic cough referred to a specialized clinic at McMaster University with sputum eosinophilia ≥2% were enrolled in the study and grouped as NAEB (n=8) or AA (n=13) based on methacholine PC20. Total, intracellular cytokine and neuropeptide receptor expression in sputum and blood ILC2 were enumerated by flow cytometry. <bold>Results:</bold> In sputum, total and NMUR1+ ILC2 were significantly greater in NAEB compared with AA despite comparable eosinophil levels; IL-10+ ILC2 trended higher in NAEB and IL-5/13 levels were comparable between groups. No between group differences were observed in blood. <bold>Conclusions:</bold> In NAEB, neuropeptide mediated activation of airway ILC2 may play a role in driving airway eosinophilia. 1. Zhan C et al., Allergy 2022;77:649-52 2. R. Sehmi et al., Am J Respir Crit Care Med 2022;205: A5011