Linarin Protects Against CCl₄-Induced Acute Liver Injury via Activating Autophagy and Inhibiting the Inflammatory...

Linarin has been implicated in the inhibition of inflammatory responses and hepatoprotective effects. However, the precise mechanism by which Linarin integrates injury-induced signaling from inflammatory responses and oxidative stress remains unclear.

We evaluated the role of Linarin in a mouse model of carbon tetrachloride (CCl₄)-induced acute liver injury. Mice were orally pretreated with Linarin or vehicle for seven consecutive days, followed by intraperitoneal injection with 0.2% (v/v) CCl₄. To investigate the mechanism of action on oxidative stress, CCl₄-stimulated HepG2 cells were utilized.

Our results revealed Linarin remarkably attenuated the loss of hepatic architecture, inflammatory cell infiltration, serum transaminases, and pro-inflammatory cytokines induced by CCl₄. Linarin attenuated CCl₄-induced oxidative stress by increasing the expression of cytosolic Nrf2 (nuclear factor erythroid 2-related factor 2), inducing nuclear localization of Nrf2, and increasing stress-induced protein heme oxygenase-1 (HO-1). Additionally, Linarin decreased the expression of toll-like receptors (TLR)-4, and its downstream proteins, MyD88, IRAK1, and TRAF6. Furthermore, Linarin reversed CCl₄-induced phosphorylation of ERK, p38, and JNK. Importantly, Linarin increased the expression of both LC3II and Beclin 1, which are hallmarks of autophagic flux. Autophagy-mediated hepatoprotective effects in Linarin-treated HepG2 cells were mitigated by the autophagy inhibitor 3-MA. However, combined treatment of Linarin with 3-MA failed to significantly reverse cell apoptosis and the production of transaminases and pro-inflammatory cytokines.

Linarin prevents acute liver injury, possibly by alleviating ROS-induced oxidative stress, inhibiting TLR4/MyD88 and JNK/p38/ERK-mediated inflammatory responses, and promoting Beclin 1/LC3II-mediated autophagic flux.