Serum Galectin-10: A biomarker for persistent airflow limitation in adult asthmatics

Abstract

Background: Inhaled corticosteroids (ICS) are primary anti-inflammatory medications to control eosinophilic airway inflammation, and prevent asthma exacerbation. However, persistent airflow limitation (PAL) presents in some asthmatics even on ICS treatment, leading to lung function decline. Thus, we evaluated clinical associations of serum galectin-10 (Gal10) and galectin-3 (Gal3) levels in adult asthmatics who had maintained anti-asthma medication.

Methods: Sixty-seven asthmatics and 78 healthy controls (HCs) were recruited. Serum Gal10 and Gal3 levels were measured by enzyme-linked immunosorbent assay, and their clinical relevance with inflammatory and lung function parameters was evaluated. Spirometry was performed to assess PAL and small airway dysfunction (SAD). Airway epithelial cells were cocultured with eosinophils/neutrophils, and were exposed to house dust mites to assess the production of Gal10 and Gal3.

Results: Serum Gal10 (not Gal3) levels were significantly higher in asthmatics than in HCs (P < 0.001), in asthmatics with PAL than in those without PAL (P = 0.005), and in those with SAD than in those without SAD (P = 0.004). The Gal10-high group had significantly higher levels of peripheral CD66⁺ neutrophil counts, serum periostin and Gal3, and lower values of FEV₁% and MMEF% than the Gal10-low group (P < 0.050 for all). The production of Gal10 and Gal3 was increased in eosinophilic airway model, while Gal10 (not Gal3) levels were increased in neutrophilic airway model as well as house dust mite stimulation.

Conclusion: Our findings suggest that serum Gal10 level may be a potential biomarker for PAL in adult asthmatics.

Keywords: Airway remodeling; Asthma; Eosinophils; Epithelial cells; Galectin-10; Inflammation; Neutrophils.

Fig. 1

Elevated levels of serumgalectin-10(Gal10) in adult asthmatics with persistent airflow limitation (PAL). Comparisons of serum Gal10 levels between the asthma and healthy control (HC) groups (A). Serum Gal10 (B) and galectin-3 (Gal3) (C) levels in asthmatic subjects according to PAL. Data are presented as median (interquartile range). P values were obtained by the Mann-Whitney U tests. Receiver operating characteristic curve (ROC) analysis of serum Gal10 levels for discriminating the PAL group from the non-PAL group (D). Spearman correlations between serum Gal10 levels and FEV₁% in asthmatics (E), depicted with coefficient r and P value. AUC, area under the ROC curve; FEV₁, forced expiratory volume in the first second

Fig. 2

Elevated levels of serumgalectin-10(Gal10) in adult asthmatics with small airway dysfunction (SAD). Serum Gal10 (A) and galectin-3 (Gal3) (B) levels in asthmatic subjects according to SAD. Data are presented as median (interquartile range). P values were obtained by the Mann-Whitney U tests. Receiver operating characteristic curve (ROC) analysis of serum Gal10 for discriminating the SAD group from the non-SAD group (C). Spearman correlations between serum Gal10 levels and MMEF% in asthmatics (D), depicted with coefficient r and P value. AUC, area under the ROC curve; MMEF, maximal mid-expiratory flow

Fig. 3

Correlations between serumgalectin-10(Gal10) levels and inflammatory biomarkers in asthmatic subjects. Spearman correlations between serum Gal10 levels and peripheral CD66⁺ neutrophil counts (A), serum periostin levels (B) and serum galectin-3 (Gal3) levels (C) in asthmatics, depicted with coefficient r and P values

Fig. 4

The production ofgalectin-10(Gal10) andgalectin-3(Gal3) upon eosinophilic and neutrophilic airway inflammation. The levels of Gal10 released from A549 cells in coculture with Eos/Neu or in response to EETs/NETs (n = 6 for each group) (A–B). The levels of Gal3 released from A549 in coculture with Eos/Neu or in response to EETs/NETs (n = 6 for each group) (C–D). Data are presented as geometric mean with 95% CI. P values were obtained by the Kruskal-Wallis tests. The protein expression of Gal10, Gal3, E-cadherin and Vimentin in A549 cells in response to EETs and NETs, respectively (E–F). Eosinophils, Eos; Eosinophil extracellular traps, EETs; Neutrophils, Neu; Neutrophil extracellular traps, NETs; PMA, phorbol 12-myristate 13-acetate

Fig. 5

Galectin-10 (Gal10) expression in human airway epithelial cells (AECs) in response to house dust mite. The intracellular expression of Gal10 in A549 cells in response to Der p, evaluated by confocal microscopy with DAPI (nuclear, blue) and Gal10 immunofluorescence (green) staining (A). The protein expression of Gal10 and galectin-3 (Gal3) in A549 cells in response to Der p in a time-dependent manner (0, 12, 24, 48, and 72 h), evaluated by Western blot analysis (B). The levels of Gal10 (C) and Gal3 (D) released from A549 cells in response to Der p (n = 6 for each group). Data are presented as geometric mean with 95% CI. P values were obtained by the Kruskal-Wallis tests. DAPI, 4′,6-diamidino-2-phenylindole; Der p, Dermatophagoides pteronyssinus.

Supplementary Fig. 1

Elevated levels of sputumgalectin-10(Gal10) in asthmatics with persistent airflow limitation (PAL) and small airway dysfunction (SAD). Sputum Gal10 (A) and galectin-3 (Gal3) (B) levels in asthmatic subjects according to PAL. Data are presented as median (interquartile range). P values were obtained by the Mann-Whitney U tests. Spearman correlation between sputum Gal10 levels and FEV₁% in asthmatics (C), depicted with coefficient r and P value. Sputum Gal10 (D) and Gal3 (E) levels in asthmatic subjects according to SAD. Data are presented as median (interquartile range). P values were obtained by the Mann-Whitney U tests. Spearman correlations between sputum Gal10 levels and MMEF% (F), sputum TIMP1 levels (G), sputum MMP9 levels (H), and peripheral CD66⁺ neutrophil counts (I) in asthmatics, depicted with coefficient r and P values. FEV₁, forced expiratory volume in the first second; MMEF, maximal mid-expiratory flow; MMP9, matrix metalloproteinase-9; TIMP1, tissue inhibitor of metalloproteinase-1

Supplementary Fig. 2

Elevatedgalectin-10(Gal10) expression in neutrophils according to cell activation. Strategy gating of intracellular Gal10 (medium and high expression) in neutrophils (A), detected by flow cytometry. Gal10^high neutrophil counts in neutrophil population (B). The levels of Gal10 (C) and galectin-3 (Gal3) (D) released from neutrophils in response to PMA for 30 min (n = 5 for each group). Data are presented as geometric mean with 95% CI. P values were obtained by the Kruskal-Wallis test or Mann-Whitney U tests. Co-localization of Gal10 and neutrophil elastase (NE) in neutrophils in response to PMA in a time-dependent manner (0, 10, and 30 min) (E), detected by confocal microscopy (40× oil objective) with DAPI (nuclear, blue) and immunofluorescent NE (red)/Gal10 (green) staining. DAPI, 4′,6-diamidino-2-phenylindole; PMA, phorbol 12-myristate 13-acetate