Escin suppresses immune cell infiltration and selectively modulates Nrf2/HO-1, TNF-α/JNK, and IL-22/STAT3 signaling pathways in concanavalin A-induced autoimmune hepatitis in mice

The current study aims to investigate the possible protective effect of escin, the active constituent of a natural mixture of triterpene saponin glycoside, against immune-mediated hepatitis driven by concanavalin A (Con A) and to elucidate its possible underlying mechanisms. Adult male mice were administered Con A (15 mg/kg, intravenously) for 8 h. In the treated groups, mice were pretreated with escin daily (10 mg/kg in CMC, orally) for 4 days before Con A intoxication. In addition, escin was administered in a group to examine its effect on normal mice. Our results showed that escin inhibited Con A-induced elevation in liver enzymes (ALT, AST, and LDH) and curbed the Con A-induced hepatocyte necrosis and apoptosis together with abrogating the death pathway, JNK. Coincidentally, escin has shown a reduction in neutrophil, CD4+ T cell, and monocyte infiltration into the liver. In addition, escin modulated the cellular oxidant status by compensating for the Con A-depleted expression of the transcription factor Nrf2 and the stress protein hemeoxygenase-1. These effects were in good agreement with the restraining effect of escin on Con A-instigated overexpression of NF-κB and the pro-inflammatory cytokines TNF-α and IL-17A. Interestingly, Con A provoked the cellular protective pathway IL-22/STAT3, which was revoked by the escin pretreatment. In conclusion, escin shows extended antioxidant, anti-inflammatory, antinecrotic, and anti-apoptotic effects against Con A-induced immune-mediated hepatitis. These effects may collectively be via suppressing immune cell infiltration into the liver and selective modulation of Nrf2/HO-1, TNF-α/NF-κB, TNF-α/JNK, and IL-22/STAT3 signaling pathways.