Acetyl-3-Aminoethyl Salicylate Ameliorates Hepatic Ischemia/Reperfusion Injury and Liver Graft Survival Through a High-Mobility Group Box 1/Toll-Like Receptor 4-Dependent Mechanism

In liver transplant cases, severe hepatic ischemia/reperfusion injury (HIRI) is a strong predictor of adverse liver graft and overall outcomes. During HIRI, high-mobility group box 1 (HMGB1) promotes hepatocellular death and proinflammatory cytokine secretion by toll-like receptor 4 (TLR4). Because salicylates inhibit HMGB1/TLR4 interaction, we hypothesized that salicylates may ameliorate HIRI-induced liver damage by inhibiting HMGB1/TLR4 axis activation. Using a murine model of HIRI, we found that the salicylate acetyl-3-aminoethyl salicylic acid (ac3AESA) reduced serum alanine aminotransferase and aspartate aminotransferase as well as Suzuki scores and apoptotic cell counts after HIRI. Ac3AESA also down-regulated hepatocellular HMGB1 and TLR4 expression, phosphorylated inhibitor of kappa B alpha, extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, cleaved caspase 3, and cleaved caspase 1 levels after HIRI. Ac3AESA reduced liver Kupffer cell transcription of proinflammatory mediators tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 6, IL1 beta, chemokine (C-X-C motif) ligand (CXCL) 1, CXCL2, and CXCL8 after HIRI. Ac3AESA also dose-dependently reduced in vitro release of Kupffer cell TNF-alpha. Employing a murine orthotopic liver transplantation model, we found daily ac3AESA administration up to day 10 after transplant improved liver graft survival, suppressed allograft damage, and down-regulated HMGB1/TLR4 signaling. These benefits to survival and allograft health were maintained for cold ischemia times of 12 and 18 hours. Notably, TLR4 knockout eliminated all foregoing ac3AESA-induced effects. In conclusion, ac3AESA partially rescues the negative effects of HIRI and prolongs liver graft survival in a TLR4-dependent manner.