The plant extract PNS mitigates atherosclerosis via promoting Nrf2-mediated inhibition of ferroptosis through reducing USP2-mediated Keap1 deubiquitination.

Background And Purpose: Atherosclerosis is the basis of cardiovascular disease. Ferroptosis is a form of programmed cell death characterized by lipid peroxidation, which contributes to atherogenesis. The plant extract PNS (Panax notoginseng saponins), containing the main active ingredients of Panax notoginseng, exhibits anti-atherogenic properties. Herein, we determined whether PNS and its major components could attenuate atherosclerosis by suppressing ferroptosis and revealed the underlying mechanism(s).

Experimental Approach: The anti-atherogenic effects of PNS and their association with inhibition of ferroptosis was determined in apoE mice. In vitro, the anti-ferroptotic effect and mechanism(s) of PNS components were demonstrated in the presence of ferroptosis inducers. Expression of ferroptosis markers and the ubiquitination of Keap1 were evaluated in USP2 macrophages. Finally, the anti-atherogenic effect of USP2 knockout was determined by using USP2 mice treated with high-fat diet (HFD) and AAV-PCSK9.

Key Results: PNS inhibited ferroptosis and atherosclerosis in vivo. PNS suppressed ferroptosis and ferroptosis-aggravated foam cell formation and inflammation in vitro. Mechanistically, PNS and its components activated Nrf2 by antagonizing Keap1, which was attributed to the inhibition of USP2 expression. USP2 knockout antagonized ferroptosis and ferroptosis-aggravated foam cell formation and inflammation, thus mitigating atherosclerosis. USP2 knockout abolished inhibitory effects of PNS on foam cell formation and inflammation in vitro.

Conclusion And Implications: PNS reduced USP2-mediated Keap1 de-ubiquitination and promoted Keap1 degradation, thereby activating Nrf2, improving iron metabolism and reducing lipid peroxidation, thus contributing to an anti-atherosclerotic outcome. Our study revealed the mechanism(s) underlying inhibition of ferroptosis and atherosclerosis by PNS.