Notoginsenoside R1 Counteracts Endotoxin-Induced Activation of Endothelial Cells In Vitro and Endotoxin-Induced Lethality in Mice In Vivo

Abstract

Abstract In this study we investigated a possible counteracting activity of notoginsenoside R1 (NG-R1) on lipopolysaccharide (LPS)-induced effects in vitro and in vivo. The upregulation of plasminogen activator inhibitor-1 (PAI-1) antigen due to LPS (1 μg/mL for 12 hours) in human umbilical vein endothelial cells (HUVECs) was prevented when the cells were incubated simultaneously with 100 μg/mL NG-R1 (PAI-1 antigen: LPS-treated cells, 969±54 ng/10 ⁵ cells; control cells, 370±15 ng/10 ⁵ cells; LPS+NG-R1–treated cells, 469±29 ng/10 ⁵ cells; n=6). The 2.5- and 3.4-fold (2.2- and 3.2-kb) increases in PAI-1 mRNA levels induced by LPS (1 μg/mL for 6 hours) were reduced to 1.4- and 2.6-fold increases in the presence of both LPS and 100 μg/mL NG-R1. LPS-induced tissue factor (TF) activity in HUVECs was also counteracted when the cells were coincubated with both LPS and 100 μg/mL NG-R1 for 6 hours (TF activity: LPS-treated cells, 88.6±6.5 mU/10 ⁶ cells; control cells, 0.7±0.01 mU/10 ⁶ cells; LPS+NG-R1–treated cells, 56.0±1.9 mU/10 ⁶ cells). The 26-fold increase in TF mRNA levels induced by LPS (1 μg/mL for 2 hours) was reduced to a 13-fold increase in the presence of both LPS and 100 μg/mL NG-R1. PAI activity levels in the plasma of mice 4 hours after injection of LPS (10 ng/g body wt) increased 2.3-fold compared with a control group. In contrast, PAI activity from LPS+NG-R1 (1 μg/g body wt NG-R1)–treated animals was at control level (PAI-1 activity: LPS-treated group, 11.3±3.1 U/mL; control group, 4.9±0.3 U/mL; LPS+NG-R1–treated group, 4.3±1.0 U/mL; n=5 to 8). The production of TNF-α induced by 1 μg/mL LPS by cultured human whole-blood cells was inhibited by 46% when the cells were incubated together with 100 μg/mL NG-R1. NG-R1 protected mice from the lethal effects of LPS. The 78% lethality induced by LPS/galactosamine was reduced to 23% when NG-R1 was administered simultaneously ( P <.01 by χ ² test). To extend this study to inflammatory cells, the effect of NG-R1 on LPS stimulation of the monocytic cell line THP-1 was investigated. NG-R1 inhibited the LPS-induced degradation of IκB-α and superinduced LPS-induced IκB-α mRNA, indicating that the effect of NG-R1 is not restricted to endothelial cells and is at least in part mediated by interference with the NF-κB/IκB-α pathway.