β-Caryophyllene alleviates d-galactosamine and lipopolysaccharide-induced hepatic injury through suppression of the TLR4 and RAGE signaling pathways

Abstract

Agastache rugosa (A. rugosa, Labiatae), a perennial herb spread throughout Korean fields, is widely consumed as a wild edible vegetable and is used in folk medicine. This study examined the hepatoprotective mechanisms of β-caryophyllene (BCP), a major bicyclic sesquiterpene of A. rugosa, against d-galactosamine (GalN) and lipopolysaccharide (LPS)-induced hepatic failure. Mice were given an intraperitoneal injection of BCP (50, 100 and 200mg/kg) 1h before GalN (800mg/kg)/LPS (40μg/kg) injection and were killed 1h or 6h after GalN/LPS injection. GalN/LPS markedly increased mortality and serum aminotransferase activity, both of which were attenuated by BCP. BCP also attenuated increases in serum tumor necrosis factor-α, interleukin 6, and high-mobility group protein B1 levels by GalN/LPS. GalN/LPS significantly increased toll-like receptor (TLR) 4 and receptor for advanced glycation end products (RAGE) protein expression, extracellular signal-related kinase, p38 and c-Jun N-terminal kinase phosphorylation, nuclear factor κB (NF-κB), early growth response protein-1, and macrophage inflammatory protein-2 protein expression. These increases were attenuated by BCP. Furthermore, BCP suppressed increased TLR4 and RAGE protein expression and proinflammatory cytokines production in LPS-treated isolated Kupffer cells. Our findings suggest that BCP protects against GalN/LPS-induced liver injury through down-regulation of the TLR4 and RAGE signaling.