n-butanol extract from Folium isatidis inhibits the lipopolysaccharide-induced downregulation of CXCR1 and CXCR2 on human neutrophils

Wu, Beibei; Wang, Liyin; Jiang, Lili; Dong, Lili; Xu, Fengli; Lu, Yili; Jin, Jiahui; Wang, Zhanyue; Liang, Guang; Shan, Xiaoou

IL-8, as the ligand of CXCR1 and CXCR2, is important in the regulation of neutrophil migration. Following exposure of the neutrophils to LPS for 4 h, the mRNA expression of IL-8 was significantly increased (Fig. 4A) . Therefore, the present study examined whether n-butanol extract affected the production of IL-8. The isolated neutrophils were pretreated with extract and then incubated with LPS (0.5 µg/ml) for 1 h (Fig. 4B ) or 4 h (Fig. 4C) . The expression levels of IL-8 were quantified using ELISA. A decrease in IL-8 was observed following exposure to LPS for 1 and 4 h when pretreated with the extract. Specifically, following exposure to LPS for 4 h, the cytokine expression of IL-8 was decreased >5-fold when the cells were treated with the extract at a dose of 500 µg/ml, compared with LPS stimulation (Fig. 4C) . MPO levels are a measure of neutrophil migration. Therefore, the present study examined the effect of the extract on the activity of MPO. Neutrophils were pretreated with n-butanol extract for 2 h followed by stimulation with LPS for 4 h. The activity of MPO increased in a dose-dependent manner following treatment with extract, compared with the control (Fig. 4D) , suggesting that n-butanol extract promoted the function of neutrophils.