[The mechanism of inhibition by ginkgolide B on interleukin-8 production induced by 4-hydroxynonenal in bronchial epithelial cells].

Objective: 4-Hydroxynonenal (4-HNE) can increase the synthesis of interleukin-8 (IL-8) in bronchial epithelium cells (16HBE). This study was to explore the role of ginkgolide B in inhibiting the synthesis of IL-8 induced by 4-HNE in 16HBE.

Methods: The experiments were divided into 3 groups: a group treated with 4-HNE (10 micromol/L), a group treated with ginkgolide B (100 micromol/L) + 4-HNE (10 micromol/L), and a control group. IL-8 and IL-8 mRNA were measured after 4-HNE (or serum-free medium) stimulation for 0.5, 2, 4, 8, 12 hours. The phosphorylation of ERK1/2, JNK, p38MAPK and the combining activity of AP-1 after 4-HNE stimulation for 0.5, 2, 4, 8, 12 hours were all examined. IL-8 and the combining activity of AP-1 were measured after the 16HBE were pre-incubated with 50 micromol/L PD98059 (MEK1 inhibitor) for 2 hours before 4-HNE stimulation. The combining activity of AP-1 in 10 micromol/L 4-HNE, 100 micromol/L ginkgolide B + 10 micromol/L 4-HNE, and the control groups were all measured by EMSA.

Results: The level of IL-8 in 10 micromol/L 4-HNE, 100 micromol/L ginkgolide B + 10 micromol/L 4-HNE, the control groups after 4-HNE stimulating for 4 h were (98.3 +/- 4.2), (88.2 +/- 5.3), (65.3 +/- 6. 2) and (116.5 +/- 5.6), (102.8 +/- 4.7), (63.7 +/- 6.6) microg/L for 12 h. The level of IL-8 and IL-8 mRNA after 4-HNE stimulation in the ginkgolide B + 4-HNE group were lower than those in the 4-HNE group while higher than those in the control groups. The level of phosphorylation of ERK1 in the 4-HNE group at 0.5, 2, 4, 8, 12 hours were higher than those in the control groups (t = 2.83 - 14.03, P < 0.05). The AP-1 combining activity in the 4-HNE group, the ginkgolide B + 4-HNE group, PD98059 + 4-HNE group, and the control group were significantly different (F = 21.49 - 194.16, P < 0.01). The expression of IL-8 and the AP-1 combining activity in groups of pre-incubated with PD98059 2 hours before 4-HNE stimulation were lower than that without PD98059. The combining activity of AP-1 in the ginkgolide B + 4-HNE group was decreased as compared to the 4-HNE groups.

Conclusion: 4-HNE increased the expression of Interleukin-8 in bronchial epithelium cells, via increasing the transcription activities of AP-1 by ERK1 cell signal transduction pathways. Ginkgolide B inhibited synthesis of IL-8 by blocking ERK1-AP1 transduction pathways.