Sputum TWEAK expression correlates with severity and degree of control in non‐eosinophilic childhood asthma

Background

Tumor necrosis factor‐like weak inducer of apoptosis (TWEAK) is known to play a role in the pathogenesis of various inflammatory diseases. However, no study has been performed on childhood asthma.

Methods

Ninety‐five children with asthma and 78 controls aged 5‐18 years were included. Sputum induction, pulmonary function test (PFT), and methacholine challenge test were performed. The subjects were divided into the eosinophilic airway (EA) and non‐EA (NEA) groups based on sputum analysis and into the high and low TWEAK groups according to the TWEAK cutoff level (263.0 pg/mL). TWEAK in induced sputum supernatant was measured through enzyme‐linked immunosorbent assay.

Results

Children with asthma had higher TWEAK levels than healthy controls (493.0 [157.1‐904.3] vs 118.2 (67.5‐345.5) pg/mL, P < .001). Sputum TWEAK levels were significantly correlated with PFT parameters reflecting airway obstruction. This association was particularly prominent in subjects with NEA inflammation. Significant differences in FEF_25‐75 (maximum mid‐expiratory flow, % predicted; P = .017), AX (reactance area; P < .001), R5‐R20 (difference between resistance at 5 and 20 Hz; P = .025), and X5 (reactance at 5 Hz, % predicted; P < .001) were noted between the high and low TWEAK groups within the NEA group. Sputum TWEAK level also showed significant positive correlations with asthma severity (r = .358, P = .001) and control status (r = .470, P < .001), distinctively in subjects with NEA inflammation.

Conclusions

Airway TWEAK may play a role in small airway inflammation especially in children with non‐eosinophilic asthma.