Objective: Chronic inflammation of airway in bronchial asthma is caused by many complicated elements. Recently, a close attention has been paid to the neurogenic inflammation in airway which is mediated by sensory neuropeptides secreted by sensory nerve in the lung. Neurokinin A (NKA) is an important sensory neuropeptide leading to neurogenic inflammation in airway. Experimental studies showed that NKA has a close relation to asthma. The purpose of the present study was to investigate the changes of NKA in plasma of asthmatic children and possible relationship between sensory neuropeptides and asthma in children.
Methods: Thirty-five children with bronchial asthma were studied; 16 of the cases were < 3 yrs and 19 were >or= 3 yrs. Eighteen of the cases had severe asthma and 16 had mild asthma. None of the subjects was treated with glucocorticoid within 3 days before the study started; 15 healthy children without history of asthma or family history of asthma were enrolled as control subjects. Plasma was collected from each case during acute attack of asthma and their clinical remission of the asthmatic children. After purifying with SEP-pak C(18), NKA content was detect by enzyme-linked immunosorbent assay (ELISA) as instructed by the manufacturer of the NKA Kit (NKA unit: ng/L).
Results: (1) The content of plasma NKA of asthmatic children was significantly higher at the asthma attack (256 +/- 153) than that at their clinical remission stage (70 +/- 66; q = 9.497, P < 0.01) and than that of the normal control group (38 +/- 6; q = 8.599, P < 0.01); no significant difference in plasma NKA was found between the clinical remission stage and the normal control group (q = 1.245, P > 0.05). (2) There was a significant positive correlation between the asthmatic clinical state and the levels of plasma NKA; the contents of plasma NKA at the stage of acute attack in severe asthma (296 +/- 170) were significantly higher than those of the mild asthmatic children (190 +/- 99; q = 3.77, P < 0.05).
Conclusions: The contents of plasma NKA were significantly higher during the asthma attack stage of children, and the higher was the level of NKA, the more severe the attack.; with asthma remission, the contents of plasma NKA decreased to normal; the contents of plasma NKA has a close relation to the asthmatic children.