Receptor Interacting Protein Kinase 3 Deficiency Exacerbates Cholestatic Liver Injury in Mice

Abstract

Obstructive cholestasis leads to acute and chronic liver injury. In the bile duct ligation (BDL) model, injury occurs through necrosis, and is mediated by recruited neutrophils. Receptor interacting protein kinase 3 (RIP3) is an integral mediator of programmed necrosis. Depletion of RIP3 protects against acetaminophen hepatotoxicity, and alcoholic steatohepatitis, suggesting it might be a major mediator of necrosis in the liver. The purpose of this study was to determine if RIP3 was induced during cholestatic liver injury, and to further determine if deficiency of RIP3 protects against BDL. BDL or sham surgery was carried out on wild type (WT) C57Bl/6 or RIP3‐/‐ mice and liver injury was assessed 24 and 72 hours later. RIP3 protein was induced after BDL in murine liver. Although sham WT and RIP3‐/‐ mice were similar, RIP3‐/‐ mice had significantly higher plasma ALT values than WT mice after BDL. Histological analysis confirmed the increase in injury using both H&E and TUNEL stains. RIP3‐/‐ mice also had significantly greater neutrophil infiltration than WT mice post BDL. This was despite the fact multiple genes associated with inflammation during cholestasis were not different between WT and RIP3‐/‐ mice, and there were no differences in circulating neutrophil counts in RIP3‐/‐ and WT mice before or after BDL. Interestingly, injury 6 hours post BDL was similar between groups; however, there was increased neutrophil infiltrate in the RIP3‐/‐ mice, indicating the increase in neutrophils occurred before the increase in injury. In conclusion, these data indicate RIP3‐/‐ mice are more susceptible to cholestatic liver injury, likely through enhanced and sustained accumulation of cytotoxic neutrophils.