Persistent airway inflammation and bronchial hyperresponsiveness in patients with totally controlled asthma

A proportion of asthmatic patients can achieve total control according to the Global Initiative for Asthma/National Institute of Health guidelines. The aim of this study was to investigate whether total control of asthma is accompanied by the remission of airway inflammation and bronchial hyperresponsiveness.

We assessed the number of eosinophil and the levels of eosinophil cationic protein (ECP) and interleukin (IL)-5 in induced sputum and bronchial responsiveness to methacholine in 76 patients with totally controlled asthma in comparison with 30 current untreated asthmatics and 20 healthy subjects.

We found significantly higher number of eosinophil and higher levels of ECP and IL-5 in the total control group than those in healthy subjects (6.9% +/- 3.6% and 1.3% +/- 1.1%, 129.0 +/- 53.8 mug/l and 48.9 +/- 20.4 mug/l, 22.1 +/- 15.2 mug/l and 10.6 +/- 5.2 mug/l, respectively; p < 0.001), but lower than those in current asthma group (16.2% +/- 8.6%, 362.2 +/- 151.6 mug/l, 50.6 +/-25.8 mug/l, respectively; p < 0.001). Sixty-five (85.5%) patients with totally controlled asthma showed positive methacholine challenge test. In the total control group, number of eosinophil and the levels of ECP and IL-5 in induced sputum of patients with negative methacholine challenge test were significantly lower than those in subjects with positive methacholine challenge test (p < 0.001), whereas sputum number of eosinophil and the levels of ECP and IL-5 in patients with negative methacholine challenge test and those of healthy subjects were similar (p > 0.05).

The results of this study suggest that airway inflammation and bronchial hyperresponsiveness still persisted during total control of asthma.