Visualization of intrahepatic activation of coagulation and its contribution to disease progression in mice with acetaminophen-induced acute liver injury.

BACKGROUND: Acute liver failure (ALF) is a life-threatening disease that is most often caused by acetaminophen overdose. ALF is characterized by profound hemostatic changes, and experimental evidence suggests that activation of coagulation contributes to disease progression.

OBJECTIVES: In this study, we aimed to study and visualize intrahepatic activation of coagulation in a mouse model of acetaminophen-induced acute liver injury.

METHODS: Acute liver injury was induced by intraperitoneal injection of a hepatotoxic dose of acetaminophen in mice. Thrombin generation and the influx of platelets and neutrophils were imaged in mouse livers via intravital microscopy. To determine the contribution of coagulation activation to the progression of disease, we treated mice with argatroban, DNase I, or saline (n = 6 per group). Liver injury was determined by measurement of plasma alanine transferase (ALT) levels and histology (hematoxylin and eosin staining).

RESULTS: Acetaminophen challenge produced extensive liver injury, intrahepatic platelet aggregation, and neutrophil influx into the injured liver at 6 and 24 hours after challenge. Interestingly, we observed bursts of thrombin activity in extravascular spaces within the liver, appearing to localize within the columns of hepatocytes and in the space of Disse. Mice treated with argatroban prior to acetaminophen challenge showed a remarkable reduction in liver injury and platelet aggregation with levels similar to controls. In these mice, we did not observe intrahepatic thrombin activity. DNase treatment had no effect on liver injury or intrahepatic thrombin activity.

CONCLUSION: Acetaminophen-induced acute liver injury in mice results in generation of thrombin, formation of platelet aggregates, and influx of neutrophils in the injured liver. Intrahepatic thrombin generation likely contributes to liver injury as pretreatment with argatroban reduced hepatic injury. DNase treatment did not impact acetaminophen-induced intrahepatic activation of coagulation or liver injury in mice, implying a minimal role for neutrophil extracellular traps or extracellular DNA in these processes.