[The levels of nerve growth factor and IL-4 in induced sputum and characteristics of airway inflammation in cough variant asthma].

OBJECTIVE

To observe sputum cytology counts, the levels of nerve growth factor (NGF) and IL-4 in cough variant asthma (CVA) patients and the change of their levels after using glucocorticoids combined with β(2)-adrenergic agonists one month, and to investigate CVA's characteristics of airway inflammation.

METHODS

Totally 36 patients with untreated CVA were selected, as well as 23 healthy controls. Coughed up sputum cells were obtained and HE strained for differential cell counting in each enrolled patient. In induced sputum's supernatant, the levels of NGF and IL-4 were determined by ELISA.

RESULTS

Before treatment, CVA patients had a median eosinophils (EOS) percentage of 8%, which was significantly higher than that after treatment (2%, P < 0.05) and in healthy control group (1%, P < 0.001). The levels of NGF and IL-4 in induced sputum of CVA group were (9.50 ± 1.69) ng/L and (257.37 ± 53.57) ng/L. After treatment, they were (8.78 ± 1.02) ng/L and (228.60 ± 52.93) ng/L in CVA group, (6.98 ± 0.69) ng/L and (166.44 ± 24.75) ng/L in healthy control group. The levels of NGF and IL-4 before and after treatment in the CVA group, as compared with the healthy control group, had statistically significant differences (all P < 0.001). In CVA group before and after treatment, the level of NGF and IL-4 paired difference was significant (P < 0.001). The percentage of induced sputum EOS correlated with sputum supernatant concentrations of NGF and IL-4 (P < 0.01). In induced sputum supernatant, the concentrations of NGF and IL-4 were significant correlated (P < 0.01).

CONCLUSIONS

Glucocorticoid joint long-term β(2) agonist inhaled treatment significantly reduced NGF, IL-4 and EOS levels and reduced eosinophilic inflammation, which are closely related with the nerve-immune mechanism, NGF as well as IL-4 participated the inflammation. Induced sputum examination is non-invasive, economical, simple, easily accepted by patients, and repeatable, widely used in clinical.