Associations Between Blood Eosinophil Surface Proteins and Clinical Traits in Severe Asthma and Chronic Rhinosinusitis With Nasal Polyposis
Severe asthma and chronic rhinosinusitis with nasal polyposis (CRSwNP) are airway diseases mostly caused by type 2 (T2) inflammation, in which eosinophils play an important role [1]. Severe asthma is characterised by persistent symptoms despite high doses of corticosteroids, which can lead to long-term side effects [2]. Consequently, biologics have been developed, including those targeting eosinophils through interleukin-5 (IL-5) or its receptor. However, these therapies do not uniformly suppress eosinophil activity [3], suggesting heterogeneity among eosinophil populations and differential sensitivity to treatments. In atopic dermatitis, another T2 inflammatory disorder, we have previously demonstrated that blood eosinophils display unique surface markers compared to healthy individuals [4]. Therefore, this study aimed to determine whether circulating eosinophils in patients with severe asthma or CRSwNP display altered surface marker expression in comparison to healthy controls. Furthermore, we assessed whether specific surface markers correlate with diseases clinical features. The description and characteristics of the participants included in the study are presented in Table 1 and the Document S1. The levels of surface markers were examined by flow cytometry as described in the Document S1. Among the surface markers, CD123 and CD125 are critical receptors for interleukin-3 (IL-3) and IL-5 involved in eosinophil differentiation, migration and survival. We also analysed Siglec-8, a marker of mature eosinophils and mast cells that reduces eosinophil activity [5] and chemokine receptors, CCR3 and CRTH2, binding the eotaxins and prostaglandin D2, respectively. Additionally, we assessed adhesion molecules (CD44 and CD62-L) and eosinophil activation markers (CD63, CD69, CD137, HLA-DR). Among all analysed markers, only CD125 was significantly higher on eosinophils from patients with severe asthma and in patients with CRSwNP compared to healthy controls (Figure 1A and Data S1 Figure 1B). We then performed correlation analyses between surface marker levels and clinical features (Figure 1B,C). In severe asthma, higher levels of HLA-DR, CD69, and CD44 correlated with poorer asthma control, as determined by the Asthma Control Test (ACT) or the Asthma Control Questionnaire (ACQ-6). Furthermore, increased airflow limitation, assessed via the Forced Exhaled Volume in 1 s/forced vital capacity ratio (FEV1/FVC), was associated with increased CD123 on eosinophils. CD62-L expression inversely correlates with age at disease onset and fractional exhaled nitric oxide (FeNO), the latter of which indicates greater T2 airway inflammation in patients with low CD62-L (Figure 1B). However, unlike Mesnil et al. [6], we did not identify distinct eosinophil subsets based on CD62-L and CD123 in either patients or controls. The number of exacerbations, total serum IgE levels and inhaled corticosteroid dose did not show significant correlations (Figure S2A). In CRSwNP, CCR3 level inversely correlated with nasal polyp score (NPS), whereas CD63 showed a positive correlation (Figure 1C). These significant associations are further illustrated in Figure S2B. We also performed correlation analyses between surface marker expressions (Table S1). However, due to the limited sample size, we did not pursue more complex multivariate clustering approaches at this stage. In conclusion, this is a study analysing human blood eosinophil surface markers in patients with severe asthma and CRSwNP. Variability among participants and limited sample size may have restricted the number of statistically significant outcomes. However, we observed a high surface expression of CD125 in severe asthma and CRSwNP compared to controls. This finding highlights the potential of using eosinophil phenotyping to identify patients who may respond to anti-IL-5 and IL-5 receptor therapy despite a moderate eosinophil count. Furthermore, we identified specific eosinophil surface markers (i.e., HLA-DR, CD69, CD44, CCR3) correlated with phenotypic and treatable traits (ACT, ACQ-6, NPS), providing potential biomarkers of airway diseases. Further research is needed to confirm the utility of eosinophil surface protein profiling in predicting disease features and therapeutic response. All authors have contributed significantly to the study. C. Chenivesse declares research grants from AstraZeneca, GSK, Santelys, and Novartis; personal fees from ALK-Abello, AstraZeneca, Boehringer-Ingelheim, Celtrion, Chiesi, Sanofi, and GSK; and congress support from AstraZeneca, Boehringer Ingelheim, Chiesi, Sanofi, and Novartis. G. Lefèvre received consulting fees, personal fees for advisory boards or meetings, and research funding from AstraZeneca and GSK. The rest of the authors declare that they have no relevant conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request. Data S1: all70001-sup-0001-DataS1.zip. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
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