Dissociating hepatocellular necrosis from hepatic encephalopathy: a murine acetaminophen model to identify second-hit drivers of acute liver failure

Acetaminophen (i.e. paracetamol; APAP) overdose is the most common cause of acute liver injury in the United States, yet outcomes range from recovery to acute liver failure (ALF), defined by coagulopathy and hepatic encephalopathy (HE). Clinical decision-making is difficult because routine indices of hepatocellular injury (e.g. ALT/AST) do not reliably predict which patients will recover versus progress to ALF. This underscores the need to define mechanisms that drive progression to ALF and to discover biomarkers that better predict clinical trajectory. A major barrier is the lack of an experimentally tractable model in which severe hepatocellular injury is comparable, but neurological outcome diverges-a defining feature of human APAP toxicity. To address this, we established APAP dosing conditions in mice that produce similar peak liver injury yet distinct clinical courses. Mice treated with 300 mg/kg or 500 mg/kg APAP exhibited comparable increases in ALT and hepatic necrosis. In contrast, only 500 mg/kg APAP caused robust neurological dysfunction consistent with HE, including impaired reflex integrity and motor coordination, accompanied by cerebral edema and reduced cerebral blood flow. Hyperammonemia is widely implicated in HE, but ammonia levels do not always track with HE severity in patients, suggesting additional cooperating factors. Consistent with this clinical discordance, blood ammonia increased to a similar extent in both dosing groups despite clear divergence in neurological impairment. Together, these findings establish a patient-relevant platform that dissociates hepatocellular necrosis (and hyperammonemia) from HE, enabling identification of mediators that drive neurovascular dysfunction and the transition from severe liver injury to ALF.