Non-invasive identification of brain signatures of acute liver injury

<b>Background:</b> In many disorders, metabolic and inflammatory derangements that originate in peripheral organs have a deleterious impact on the brain. Brain functional impairment, defined as <i>hepatic encephalopathy,</i> is one of the main diagnostic criteria for acute liver failure (ALF), a severe complication of acute liver injury (ALI). While brain inflammation (neuroinflammation) and metabolic alterations significantly contribute to hepatic encephalopathy, their non-invasive evaluation remains challenging. <b>Methods:</b> To address this limitation, we utilized dual radiotracer [¹⁸F]-fluoro-2-deoxy-2-D-glucose ([¹⁸F]FDG) and [¹¹C]-peripheral benzodiazepine receptor ([¹¹C]PBR28) microPET imaging followed by conjunction analysis and metabolic connectivity mapping. We applied this advanced methodology in mice with high dose acetaminophen (N-acetyl-p-aminophenol, APAP)-induced ALI, which can progress into ALF. <b>Results:</b> We observed hepatocellular damage, liver and systemic inflammation, and increased density of hippocampal microglia in mice with ALI. MicroPET imaging analysis characterized the presence of brain region-specific neuroinflammation and altered brain energy metabolism in mice with ALI. We also identified both gains and losses in connectivity, as well as a dual role of neuroinflammation. These results revealed brain "neuroinflammetabolic" signatures of ALI. <b>Conclusion:</b> These findings provide a platform for non-invasively diagnosing early signs of hepatic encephalopathy with the goal of informing timely diagnoses and targeted therapies. Our approach can be further utilized in non-invasive brain assessments in liver diseases and other disorders classically characterized by peripheral immune and metabolic dysregulation.