[The effect of inhaled glucocorticosteroid on protein kinase C alpha expression and interleukin-5 production in induced sputum inflammatory cells of asthma patients].

OBJECTIVE: To investigate the expression of protein kinase C alpha (PKC alpha) in inflammatory cells and the level of interleukin-5 (IL-5) in induced sputum in asthma patients and the effect of inhaled glucocorticosteroid on them. METHODS: 29 asthma patients were classified into 2 groups; 14 patients were treated with fluticasone propionate for 2 weeks and the others were treated with fluticasone propionate for 4 weeks. Induced sputum with inhaled hypertonic saline (4% - 5%) was collected. 13 healthy volunteers were included as controls. Lung ventilatory function and forced expiratory volume in one second (FEV(1)) were measured in all patients. The expression of PKC alpha in the inflammatory cells was detected using immunocytochemistry and the positive percentage in different cells was counted. IL-5 in sputum supernatants was detected using enzyme-linked immunosorbent assay. RESULTS: The percentage of eosinophils (11.1 +/- 4.3)%, lymphocytes (4.3 +/- 2.6)%, PKC alpha positive cells (79.0 +/- 9.6)% and the concentration of IL-5 (64.9 +/- 46.0) ng/L in asthmatics were higher than the percentage of eosinophils (0.7 +/- 0.5)%, lymphocytes (1.1 +/- 0.5)%, PKC alpha positive cells (10.5 +/- 2.3)% and the concentration of IL-5 (14.3 +/- 8.4) ng/L in the controls (P < 0.01). The percentage of PKC alpha positive cells and the concentration of IL-5 in the two groups of asthma were lower than that before fluticasone propionate treatment (P < 0.05), and the forced expiratory volume in first second was correlated to them (respectively, r = -0.423, P < 0.05; n = 29, r = -0.664, P < 0.01). The concentration of IL-5 was correlated to the percentage of PKC alpha positive cells (n = 29, r = 0.623, P < 0.01). CONCLUSIONS: PKC alpha in the inflammatory cells and IL-5 may play an important part in airway inflammation, and the signal transduction of the PKC alpha may be one of the mechanisms of the airway inflammation in asthma. Glucocorticosteroid could suppress the expression of PKC alpha in airway inflammatory cells and then decrease the production of IL-5 in asthmatic airways.