Kaempferol-induced GPER upregulation attenuates atherosclerosis via the PI3K/AKT/Nrf2 pathway

Abstract

Context

The effect of kaempferol, a regulator of oestrogen receptors, on atherosclerosis (AS) and the underlying mechanism is elusive.

Objective

To explore the effect and mechanism of kaempferol on AS.

Methods and materials

In vivo, C57BL/6 and apolipoprotein E (APOE)^–/– mice were randomly categorized into six groups (C57BL/6: control, ovariectomy (OVX), high-fat diet (HFD); APOE^–/–: OVX-HFD, OVX-HFD + kaempferol (50 mg/kg) and OVX-HFD + kaempferol (100 mg/kg) and administered with kaempferol for 16 weeks, intragastrically. Oil-Red and haematoxylin–eosin (HE) staining were employed to examine the effect of kaempferol. In vitro, human aortic endothelial cells (HAECs) were pre-treated with or without kaempferol (5, 10 or 20 μM), followed by administration with kaempferol and oxidized low-density lipoprotein (ox-LDL) (200 μg/mL). The effect of kaempferol was evaluated using flow cytometry, and TdT-mediated dUTP Nick-End Labelling (TUNEL).

Results

In vivo, kaempferol (50 and 100 mg/kg) normalized the morphology of blood vessels and lipid levels and suppressed inflammation and apoptosis. It also activated the G protein-coupled oestrogen receptor (GPER) and PI3K/AKT/nuclear factor-erythroid 2-related factor 2 (Nrf2) pathways. In vitro, ox-LDL (200 μg/mL) reduced the cell viability to 50% (IC₅₀). Kaempferol (5, 10 or 20 μM) induced-GPER activation increased cell viability to nearly 10%, 19.8%, 30%, and the decreased cellular reactive oxygen species (ROS) generation (16.7%, 25.6%, 31.1%), respectively, consequently attenuating postmenopausal AS. However, the protective effects of kaempferol were blocked through co-treatment with si-GPER.

Conclusions

The beneficial effects of kaempferol against postmenopausal AS are associated with the PI3K/AKT/Nrf2 pathways, mediated by the activation of GPER.

Keywords:

• Inflammation
• apoptosis
• traditional Chinese medicines (TCM)
• oxidized low-density lipoprotein (ox-LDL)

Disclosure statement

All authors declare that there are no conflicts of interest.

Data availability statement

The data used to support the findings of this study are available from the corresponding author upon request.

Additional information

Funding

The work was supported in part by Grants from the National Natural Science Foundation of China (No. 82073851) and Natural Science Fund of Science and Technology Bureau of Liaoning Province (No. 20180530065).