The effect of Ginkgo Biloba extract on the expression of PKCalpha in the inflammatory cells and the level of IL-5 in induced sputum of asthmatic patients.

To investigate the effect of the Ginkgo Biloba Extract (GBE) on the asthma and examine its possible mechanisms, 75 asthma patients were divided into 4 groups and the patients were respectively treated with fluticasone propionate for 2 weeks or 4 weeks, or treated with fluticasone propionate plus GBE for 2 weeks or 4 weeks. Fifteen healthy volunteers served as healthy controls. Sputum inhalation with inhaling hypertonic saline (4%-5%) was performed. Lung ventilatory function and forced expiratory volume in one second (FEV1) were measured. The numbers of different cells in induced sputum were calculated. The expression of PKCalpha in the cells was immunocytochemically detected and the percentages of positive cells in different cells were counted. Interleukin-5 (IL-5) in sputum supernatants was detected with enzyme-linked immunosorbent assay. The percentage of eosinophils, lymphocytes, PKCalpha positive inflammatory cells and the concentration of IL-5 in asthmatic patients were higher than those in the controls (P<0.05), and the eosinophils, lymphocytes, positive expression of PKCalpha and the level of IL-5 were significantly decreased in asthmatic patients after they were treated with fluticasone propionate or fluticasone propionate plus GBE. However, they were still significantly higher than those of the controls. Compared to the group treated with glucocorticosteroid for 2 weeks, no significant decrease was found in the percentage of eosinophils, lymphocytes, PKCalpha positive inflammatory cells and the IL-5 in the supernatant of induced sputum. Compared with the group treated with glucocorticosteroid for 2 or 4 weeks, significant decrease in the same parameters was observed in the group treated with fluticasone propionate and GBE for 4 weeks. The IL-5 level in the supernatant of induced sputum was positively correlated with the percentage of PKCalpha-positive inflammatory cells and the percentage of eosinophils in the induced sputum in asthma patient groups respectively (n=150, r= 0.83, P<0.01; n=150, r=0.76, P<0.01). The FEV1 was negatively correlated with the percentage of PKCalpha-positive inflammatory cells and the IL-5 levels in supernatant of induced sputum in asthma patients respectively (n=150, r=-0.77, P<0.01; n=150, r= -0.64, P<0.01). It is concluded that GBE could significantly decrease the infiltration of inflammatory cells such as eosinophils and lymphocytes in the asthmatic airway and relieve the airway inflammation. GBE may decrease the activation of the PKCalpha in the inflammatory cells and thereby decrease the IL-5 level in induced sputum. GBE may be used as a complement to the glucocorticosteroid therapy for asthma.