Mixed cell type in airway inflammation is the dominant phenotype in asthma patients with severe chronic rhinosinusitis

Abstract

Background: Asthma often coexists with chronic rhinosinusitis (CRS). Recent studies revealed that sinus inflammation in asthmatic patients was related to eosinophilic inflammation. However, the relationship between the severity of CRS and four different sputum inflammatory phenotypes as defined by the proportion of eosinophils and neutrophils is unknown. The aim of this study was to examine the impact of the severity of CRS on lower airway and systemic inflammation in asthmatic patients. Methods: We enrolled 57 adult asthmatic patients who underwent sinus computed tomography (CT). The severity of CRS was evaluated by the Lund-Mackay score (LMS). The induced sputum inflammatory phenotype was defined by eosinophils (≥/<2%) and neutrophils (≥/<60%). Peripheral blood mononuclear cells (PBMC) were collected to examine cytokine productions. Results: The median LMS of subjects was 6 (interquartile range, 0–11.5). The sputum inflammatory cell phenotype was categorized as paucicellular (n = 14), neutrophilic (n = 11), eosinophilic (n = 20), or mixed (n = 12). LMS was positively correlated with the percentage of blood eosinophils, sputum eosinophils, and mean fluorescence intensity (MFI) of IL-5 on CD4+ T cells. In the severe CRS group (LMS, 12–24), the number of mixed cellular phenotypes was higher than that in the group without CRS (LMS, 0–4) and mild-to-moderate CRS group (LMS, 5–11). Conclusions: In asthmatic patients with severe CRS, the proportion of the mixed cellular inflammatory phenotype was increased as well as eosinophilic inflammation. Keywords: Asthma, Chronic rhinosinusitis, IL-5, Lund-Mackay score, Sputum inflammatory phenotype