Microbiota in HE pathogenesis. Gut bacterial phenylalanine decarboxylase induces brain phenylethylamine accumulation and neurotoxicity in liver failure

Current evidence suggests a causative link between gut microbiota dysbiosis and hepatic encephalopathy (HE), but the precise mechanism is unclear. Here we report a novel pathogenic mechanism for HE driven by microbiota dysbiosis in both mice and patients with liver failure. We found that serum phenylethylamine (PEA), rather than other monoamines, was elevated in HE patients and outperformed ammonia in HE diagnosis (n = 78, AUC: 0.681 vs. 0.743).