Ginsenoside Rh1 protects human endothelial cells against lipopolysaccharide-induced inflammatory injury through inhibiting TLR2/ 4-mediated STAT3, NF-?B, and ER stress signaling pathways

Aim: Endothelial cell (EC) dysfunction initiates atherosclerosis by inducing inflammatory cytokines and adhesion molecules. Herein, we investigated the role of ginsenoside Rh1 (Rh1) in lipopolysaccharide (LPS)-induced EC dysfunction.Main methods: The inhibitory effect of Rh1 on LPS binding to toll-like receptor 2 (TLR2) or TLR4 was evaluated using an immunofluorescence (IF) assay. Annexin V and cleaved caspase-3-positive EC apoptosis were evaluated by flow cytometry and IF assay. Western blotting and quantitative reverse transcription-PCR were performed to clarify underlying molecular mechanisms. In vivo model, effect of Rh1 on EC dysfunction was evaluated by using en face IF assay on aortas isolated C57BL/6 mice. Key finding: LPS (500 ng/mL) activated inflammatory signaling pathways, including ERK1/2, STAT3, and NF-kappa B. Interestingly, Rh1 significantly abolished the binding of LPS to TLR2 and TLR4. Consistently, Rh1 inhibited LPS-induced NF-kappa B activation and its downstream molecules, including inflammatory cytokines and adhesion mol-ecules. Furthermore, Rh1 alleviated LPS-induced downregulation of eNOS promoter activity. Notably, inacti-vation of eNOS by 50 mu M L-NAME significantly increased NF-& UKappa;B promoter activity. In addition, Rh1 abolished LPS-mediated cell cycle arrest and EC apoptosis by inhibiting endoplasmic reticulum stress via PERK/CHOP/ ERO1-alpha signaling pathway. Consistent with in vitro experimental data, Rh1 effectively suppressed LPS-induced VCAM-1 and CHOP expression and rescuing LPS-destroyed tight junctions between ECs as indicated in ZO-1 expression on mice aorta. Significance: Rh1 suppresses LPS-induced EC inflammation and apoptosis by inhibiting STAT3/NF-& UKappa;B and endoplasmic reticulum stress signaling pathways, mediated by blocking LPS binding-to TLR2 and TLR4. Consistently, Rh1 effectively reduced EC dysfunction in vivo model.